Sounding Reference Signal Transmission in a Wireless Network

ABSTRACT

Methods, apparatuses, and systems for wireless communications are described. A wireless device may receive a message comprising: a timing advance command (TAC) for a secondary cell group, and a power control command. The wireless device may transmit one or more sounding reference signals via a secondary cell of the secondary cell group, in response to applying the TAC. The wireless device may use a transmission power that may be based on the power control command.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/201,529, filed Jul. 4, 2016, which is a continuation of U.S. patentapplication Ser. No. 14/880,312, filed Oct. 12, 2015, which is acontinuation of U.S. patent application Ser. No. 14/597,483, filed Jan.15, 2015, which is a continuation of U.S. patent application Ser. No.13/749,693, filed Jan. 25, 2013, which claims the benefit of U.S.Provisional Application No. 61/590,366, filed Jan. 25, 2012, and U.S.Provisional Application No. 61/618,830, filed Apr. 1, 2012, all of theabove of which are hereby incorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings, in which:

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention;

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers in a carrier group as per an aspect of anembodiment of the present invention;

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention;

FIG. 4 is a block diagram of a base station and a wireless device as peran aspect of an embodiment of the present invention;

FIG. 5 is a block diagram depicting a system for transmitting datatraffic over an OFDM radio system as per an aspect of an embodiment ofthe present invention;

FIG. 6 is a diagram depicting uplink transmission timing of one or morecells in a first timing advance group (TAG) and a second TAG as per anaspect of an embodiment of the present invention;

FIG. 7 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention;

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present invention;

FIG. 9 is an example physical random access channel (PRACH)configuration in a primary TAG (pTAG) and a secondary TAG (sTAG) as peran aspect of an embodiment of the present invention;

FIG. 10 is an example flow diagram illustrating timing reference changeas per an aspect of an embodiment of the present invention;

FIG. 11 is an example flow diagram illustrating an unsuccessful randomaccess process as per an aspect of an embodiment of the presentinvention;

FIG. 12 is an example flow diagram illustrating an unsuccessful randomaccess process as per an aspect of an embodiment of the presentinvention;

FIG. 13 is an example flow diagram illustrating an unsuccessful randomaccess process as per an aspect of an embodiment of the presentinvention;

FIG. 14 is an example flow diagram illustrating mechanisms in a wirelessdevice when a time alignment timer expires as per an aspect of anembodiment of the present invention;

FIG. 15 is an example flow diagram illustrating a base station processfor configuring multiple cell groups as per an aspect of an embodimentof the present invention; and

FIG. 16 is an example flow diagram illustrating a process for soundingtransmission as per an aspect of an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention enable operation ofmultiple timing advance groups. Embodiments of the technology disclosedherein may be employed in the technical field of multicarriercommunication systems. More particularly, the embodiments of thetechnology disclosed herein may relate to operation of multiple timingadvance groups.

Example embodiments of the invention may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CDMA (codedivision multiple access), OFDM (orthogonal frequency divisionmultiplexing), TDMA (time division multiple access), Wavelettechnologies, and/or the like. Hybrid transmission mechanisms such asTDMA/CDMA, and OFDM/CDMA may also be employed. Various modulationschemes may be applied for signal transmission in the physical layer.Examples of modulation schemes include, but are not limited to: phase,amplitude, code, a combination of these, and/or the like. An exampleradio transmission method may implement QAM (quadrature amplitudemodulation) using BPSK (binary phase shift keying), QPSK (quadraturephase shift keying), 16-QAM, 64-QAM, 256-QAM, and/or the like. Physicalradio transmission may be enhanced by dynamically or semi-dynamicallychanging the modulation and coding scheme depending on transmissionrequirements and radio conditions.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention. As illustrated in thisexample, arrow(s) in the diagram may depict a subcarrier in amulticarrier OFDM system. The OFDM system may use technology such asOFDM technology, SC-OFDM (single carrier-OFDM) technology, or the like.For example, arrow 101 shows a subcarrier transmitting informationsymbols. FIG. 1 is for illustration purposes, and a typical multicarrierOFDM system may include more subcarriers in a carrier. For example, thenumber of subcarriers in a carrier may be in the range of 10 to 10,000subcarriers. FIG. 1 shows two guard bands 106 and 107 in a transmissionband. As illustrated in FIG. 1, guard band 106 is between subcarriers103 and subcarriers 104. The example set of subcarriers A 102 includessubcarriers 103 and subcarriers 104. FIG. 1 also illustrates an exampleset of subcarriers B 105. As illustrated, there is no guard band betweenany two subcarriers in the example set of subcarriers B 105. Carriers ina multicarrier OFDM communication system may be contiguous carriers,non-contiguous carriers, or a combination of both contiguous andnon-contiguous carriers.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentinvention. A multicarrier OFDM communication system may include one ormore carriers, for example, ranging from 1 to 10 carriers. Carrier A 204and carrier B 205 may have the same or different timing structures.Although FIG. 2 shows two synchronized carriers, carrier A 204 andcarrier B 205 may or may not be synchronized with each other. Differentradio frame structures may be supported for FDD (frequency divisionduplex) and TDD (time division duplex) duplex mechanisms. FIG. 2 showsan example FDD frame timing. Downlink and uplink transmissions may beorganized into radio frames 201. In this example, radio frame durationis 10 msec. Other frame durations, for example, in the range of 1 to 100msec may also be supported. In this example, each 10 msec radio frame201 may be divided into ten equally sized subframes 202. Other subframedurations such as including 0.5 msec, 1 msec, 2 msec, and 5 msec mayalso be supported. Subframe(s) may consist of two or more slots 206. Forthe example of FDD, 10 subframes may be available for downlinktransmission and 10 subframes may be available for uplink transmissionsin each 10 msec interval. Uplink and downlink transmissions may beseparated in the frequency domain. Slot(s) may include a plurality ofOFDM symbols 203. The number of OFDM symbols 203 in a slot 206 maydepend on the cyclic prefix length and subcarrier spacing.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention. The resource grid structure intime 304 and frequency 305 is illustrated in FIG. 3. The quantity ofdownlink subcarriers or resource blocks (RB) (in this example 6 to 100RBs) may depend, at least in part, on the downlink transmissionbandwidth 306 configured in the cell. The smallest radio resource unitmay be called a resource element (e.g. 301). Resource elements may begrouped into resource blocks (e.g. 302). Resource blocks may be groupedinto larger radio resources called Resource Block Groups (RBG) (e.g.303). The transmitted signal in slot 206 may be described by one orseveral resource grids of a plurality of subcarriers and a plurality ofOFDM symbols. Resource blocks may be used to describe the mapping ofcertain physical channels to resource elements. Other pre-definedgroupings of physical resource elements may be implemented in the systemdepending on the radio technology. For example, 24 subcarriers may begrouped as a radio block for a duration of 5 msec. In an illustrativeexample, a resource block may correspond to one slot in the time domainand 180 kHz in the frequency domain (for 15 kHz subcarrier bandwidth and12 subcarriers).

According to some embodiments, a radio resource framework using OFDMtechnology may be employed. Alternative embodiments may be implementedemploying other radio technologies. Example transmission mechanismsinclude, but are not limited to: CDMA, OFDM, TDMA, Wavelet technologies,and/or the like. Hybrid transmission mechanisms such as TDMA/CDMA, andOFDM/CDMA may also be employed.

FIG. 4 is an example block diagram of a base station 401 and a wirelessdevice 406, as per an aspect of an embodiment of the present invention.A communication network 400 may include at least one base station 401and at least one wireless device 406. The base station 401 may includeat least one communication interface 402, at least one processor 403,and at least one set of program code instructions 405 stored innon-transitory memory 404 and executable by the at least one processor403. The wireless device 406 may include at least one communicationinterface 407, at least one processor 408, and at least one set ofprogram code instructions 410 stored in non-transitory memory 409 andexecutable by the at least one processor 408. Communication interface402 in base station 401 may be configured to engage in communicationwith communication interface 407 in wireless device 406 via acommunication path that includes at least one wireless link 411.Wireless link 411 may be a bi-directional link. Communication interface407 in wireless device 406 may also be configured to engage in acommunication with communication interface 402 in base station 401. Basestation 401 and wireless device 406 may be configured to send andreceive data over wireless link 411 using multiple frequency carriers.According to some of the various aspects of embodiments, transceiver(s)may be employed. A transceiver is a device that includes both atransmitter and receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in communicationinterface 402, 407 and wireless link 411 are illustrated in FIG. 1, FIG.2, and FIG. 3, and associated text.

FIG. 5 is a block diagram depicting a system 500 for transmitting datatraffic generated by a wireless device 502 to a server 508 over amulticarrier OFDM radio according to one aspect of the illustrativeembodiments. The system 500 may include a Wireless CellularNetwork/Internet Network 507, which may function to provide connectivitybetween one or more wireless devices 502 (e.g., a cell phone, PDA(personal digital assistant), other wirelessly-equipped device, and/orthe like), one or more servers 508 (e.g. multimedia server, applicationservers, email servers, or database servers) and/or the like.

It should be understood, however, that this and other arrangementsdescribed herein are set forth for purposes of example only. As such,those skilled in the art will appreciate that other arrangements andother elements (e.g., machines, interfaces, functions, orders offunctions, etc.) may be used instead, some elements may be added, andsome elements may be omitted altogether. Further, as in mosttelecommunications applications, those skilled in the art willappreciate that many of the elements described herein are functionalentities that may be implemented as discrete or distributed componentsor in conjunction with other components, and in any suitable combinationand location. Still further, various functions described herein as beingperformed by one or more entities may be carried out by hardware,firmware and/or software logic in combination with hardware. Forinstance, various functions may be carried out by a processor executinga set of machine language instructions stored in memory.

As shown, the access network may include a plurality of base stations503 . . . 504. Base station 503 . . . 504 of the access network mayfunction to transmit and receive RF (radio frequency) radiation 505 . .. 506 at one or more carrier frequencies, and the RF radiation mayprovide one or more air interfaces over which the wireless device 502may communicate with the base stations 503 . . . 504. The user 501 mayuse the wireless device (or UE: user equipment) to receive data traffic,such as one or more multimedia files, data files, pictures, video files,or voice mails, etc. The wireless device 502 may include applicationssuch as web email, email applications, upload and ftp applications, MMS(multimedia messaging system) applications, or file sharingapplications. In another example embodiment, the wireless device 502 mayautomatically send traffic to a server 508 without direct involvement ofa user. For example, consider a wireless camera with automatic uploadfeature, or a video camera uploading videos to the remote server 508, ora personal computer equipped with an application transmitting traffic toa remote server.

One or more base stations 503 . . . 504 may define a correspondingwireless coverage area. The RF radiation 505 . . . 506 of the basestations 503 . . . 504 may carry communications between the WirelessCellular Network/Internet Network 507 and access device 502 according toany of a variety of protocols. For example, RF radiation 505 . . . 506may carry communications according to WiMAX (Worldwide Interoperabilityfor Microwave Access e.g., IEEE 802.16), LTE (long term evolution),microwave, satellite, MMDS (Multichannel Multipoint DistributionService), Wi-Fi (e.g., IEEE 802.11), Bluetooth, infrared, and otherprotocols now known or later developed. The communication between thewireless device 502 and the server 508 may be enabled by any networkingand transport technology for example TCP/IP (transport controlprotocol/Internet protocol), RTP (real time protocol), RTCP (real timecontrol protocol), HTTP (Hypertext Transfer Protocol) or any othernetworking protocol.

According to some of the various aspects of embodiments, an LTE networkmay include many base stations, providing a user plane (PDCP: packetdata convergence protocol/RLC: radio link control/MAC: media accesscontrol/PHY: physical) and control plane (RRC: radio resource control)protocol terminations towards the wireless device. The base station(s)may be interconnected with other base station(s) by means of an X2interface. The base stations may also be connected by means of an S1interface to an EPC (Evolved Packet Core). For example, the basestations may be interconnected to the MME (Mobility Management Entity)by means of the S1-MME interface and to the Serving Gateway (S-GW) bymeans of the S1-U interface. The S1 interface may support a many-to-manyrelation between MMEs/Serving Gateways and base stations. A base stationmay include many sectors for example: 1, 2, 3, 4, or 6 sectors. A basestation may include many cells, for example, ranging from 1 to 50 cellsor more. A cell may be categorized, for example, as a primary cell orsecondary cell. When carrier aggregation is configured, a wirelessdevice may have one RRC connection with the network. At RRC connectionestablishment/re-establishment/handover, one serving cell may providethe NAS (non-access stratum) mobility information (e.g. TAI-trackingarea identifier), and at RRC connection re-establishment/handover, oneserving cell may provide the security input. This cell may be referredto as the Primary Cell (PCell). In the downlink, the carriercorresponding to the PCell may be the Downlink Primary Component Carrier(DL PCC), while in the uplink, it may be the Uplink Primary ComponentCarrier (UL PCC). Depending on wireless device capabilities, SecondaryCells (SCells) may be configured to form together with the PCell a setof serving cells. In the downlink, the carrier corresponding to an SCellmay be a Downlink Secondary Component Carrier (DL SCC), while in theuplink, it may be an Uplink Secondary Component Carrier (UL SCC). AnSCell may or may not have an uplink carrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,is assigned a physical cell ID and a cell index. A carrier (downlink oruplink) belongs to only one cell, the cell ID or Cell index may alsoidentify the downlink carrier or uplink carrier of the cell (dependingon the context it is used). In the specification, cell ID may be equallyreferred to a carrier ID, and cell index may be referred to carrierindex. In implementation, the physical cell ID or cell index may beassigned to a cell. Cell ID may be determined using the synchronizationsignal transmitted on a downlink carrier. Cell index may be determinedusing RRC messages. For example, when the specification refers to afirst physical cell ID for a first downlink carrier, it may mean thefirst physical cell ID is for a cell comprising the first downlinkcarrier. The same concept may apply to, for example, carrier activation.When the specification indicates that a first carrier is activated, itequally means that the cell comprising the first carrier is activated.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in wireless device, base station, radio environment, network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, traffic load, initial systemset up, packet sizes, traffic characteristics, a combination of theabove, and/or the like. When the one or more criteria are met, theexample embodiments may be applied. Therefore, it may be possible toimplement example embodiments that selectively implement disclosedprotocols.

Example embodiments of the invention may enable operation of multipletiming advance groups. Other example embodiments may comprise anon-transitory tangible computer readable media comprising instructionsexecutable by one or more processors to cause operation of multipletiming advance groups. Yet other example embodiments may comprise anarticle of manufacture that comprises a non-transitory tangible computerreadable machine-accessible medium having instructions encoded thereonfor enabling programmable hardware to cause a device (e.g. wirelesscommunicator, UE, base station, etc.) to enable operation of multipletiming advance groups. The device may include processors, memory,interfaces, and/or the like. Other example embodiments may comprisecommunication networks comprising devices such as base stations,wireless devices (or user equipment: UE), servers, switches, antennas,and/or the like.

According to some of the various aspects of embodiments, serving cellshaving an uplink to which the same time alignment (TA) applies may begrouped in a TA group (TAG). Serving cells in one TAG may use the sametiming reference. For a given TAG, a user equipment (UE) may use onedownlink carrier as the timing reference at a given time. The UE may usea downlink carrier in a TAG as the timing reference for that TAG. For agiven TAG, a UE may synchronize uplink subframe and frame transmissiontiming of the uplink carriers belonging to the same TAG. According tosome of the various aspects of embodiments, serving cells having anuplink to which the same TA applies may correspond to the serving cellshosted by the same receiver. A TA group may comprise at least oneserving cell with a configured uplink. A UE supporting multiple TAs maysupport two or more TA groups. One TA group may contain the PCell andmay be called a primary TAG (pTAG). In a multiple TAG configuration, atleast one TA group may not contain the PCell and may be called asecondary TAG (sTAG). Carriers within the same TA group may use the sameTA value and the same timing reference. In this disclosure, timingadvance group, time alignment group, and cell group have the samemeaning. Further, time alignment command and timing advance command havethe same meaning.

FIG. 6 is a diagram depicting uplink transmission timing of one or morecells in a first timing advance group (TAG1) and a second TAG (TAG2) asper an aspect of an embodiment of the present invention. TAG1 mayinclude one or more cells, TAG2 may also include one or more cells. TAGtiming difference in FIG. 6 may be the difference in UE uplinktransmission timing for uplink carriers in TAG1 and TAG2. The timingdifference may range between, for example, sub micro-seconds to about 30micro-seconds.

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present invention. In Example 1, pTAG include PCell,and sTAG includes SCell1. In Example 2, pTAG includes PCell and SCell1,and sTAG includes SCell2 and SCell3. In Example 3, pTAG includes PCelland SCell1, and sTAG1 includes SCell2 and SCell3, and sTAG2 includesSCell4. Up to four TAGs may be supported and other example TAGconfigurations may also be provided. In many examples of thisdisclosure, example mechanisms are described for a pTAG and an sTAG. Theoperation with one example sTAG is described, and the same operation maybe applicable to other sTAGs. The example mechanisms may be applied toconfigurations with multiple sTAGs.

According to some of the various aspects of embodiments, TA maintenance,pathloss reference handling and the timing reference for pTAG may followLTE release 10 principles. The UE may need to measure downlink pathlossto calculate the uplink transmit power. The pathloss reference may beused for uplink power control and/or transmission of random accesspreamble(s). A UE may measure downlink pathloss using the signalsreceived on the pathloss reference cell. The pathloss reference downlinkcell and the corresponding uplink cell may be configured to be in thesame frequency band due to the required accuracy of pathloss estimation.For SCell(s) in a pTAG, the choice of pathloss reference for cells maybe selected from and be limited to the following two options: a) thedownlink SCell linked to an uplink SCell using the system informationblock 2 (SIB2), and b) the downlink pCell. The pathloss reference forSCells in pTAG may be configurable using RRC message(s) as a part ofSCell initial configuration and/or reconfiguration. According to some ofthe various aspects of embodiments, PhysicalConfigDedicatedSCellinformation element (IE) of an SCell configuration may include thepathloss reference SCell (downlink carrier) for an SCell in pTAG.

The downlink SCell linked to an uplink SCell using the systeminformation block 2 (SIB2) may be referred to as the SIB2 linkeddownlink of the SCell. Different TAGs may operate in different bands. Inanother example, the signals in different TAGs may travel throughdifferent repeaters, or the signal of one SCell in an sTAG may travelthrough a repeater while the signal of another TAG may not go throughthe repeater. Having flexibility in SCell pathloss referenceconfiguration for SCells belonging to an sTAG may result in pathlossestimation errors due to mobility of wireless device. The wirelessdevice may autonomously change a timing reference SCell in an sTAG, butchanging pathloss reference autonomously may result in confusion in theserving eNB, specially that different cells may have different transmitpower. Therefore, both eNB configuration flexibility and autonomous UEpathloss selection for an SCell in sTAG may result in errors in pathlossestimation. For an uplink carrier in an sTAG, the pathloss reference maybe only configurable to the downlink SCell linked to an uplink SCellusing the system information block 2 (SIB2) of the SCell. No otherdownlink carrier may be configured as the pathloss reference for anSCell in an sTAG. This configuration may introduce accuracy in pathlossestimation.

According to some of the various aspects of embodiments, a UE maysuccessfully complete a random access procedure from the reception of arandom access response (RAR) message within the random access (RA)response window using a random access radio network temporary identifier(RA-RNTI). The UE may decode scheduling information for uplinktransmission in the PDCCH common search space (CSS) with RA-RNTI.According to some of the various aspects of embodiments, in addition tothe time alignment command (TAC) field, RAR for a PCell and/or SCell maycontain at least one of the following: a Random Access PreambleIdentifier (RAPID), a UL grant, a Temporary C-RNTI, a Backoff Indicator(BI), and/or the like. RAPID may be used to confirm the associationbetween RAR and the transmitted preamble. The UL grant may be employedfor uplink transmission on the cell that the preamble was transmitted.Temporary C-RNTI may be used for contention resolution in case ofcontention based random access (CBRA). A backoff indicator (BI) may beused in case of collisions and/or high load on PRACH.

To obtain initial uplink (UL) time alignment for an sTAG, eNB mayinitiate an RA procedure. In an sTAG, a UE may use one of any activatedSCells from this sTAG as a timing reference cell. In an exampleembodiment, the timing reference for SCells in an sTAG may be the SIB2linked downlink of the SCell on which the preamble for the latest RAprocedure was sent. There may be one timing reference and one timealignment timer (TAT) per TA group. TAT for TAGs may be configured withdifferent values. When the TAT associated with the pTAG expires: allTATs may be considered as expired, the UE may flush all HARQ buffers ofall serving cells, the UE may clear any configured downlinkassignment/uplink grants, and the RRC in the UE may release PUCCH/SRSfor all configured serving cells. When the pTAG TAT is not running, ansTAG TAT may not be running. When the TAT associated with sTAG expires:a) SRS transmissions may be stopped on the corresponding SCells, b) SRSRRC configuration may be released, c) CSI reporting configuration forthe corresponding SCells may be maintained, and/or d) the MAC in the UEmay flush the uplink HARQ buffers of the corresponding SCells.

Upon deactivation of the last SCell in an sTAG, the UE may not stop TATof the sTAG. In an implementation, upon removal of the last SCell in ansTAG, TAT of the TA group may not be running. RA procedures in parallelmay not be supported for a UE. If a new RA procedure is requested(either by UE or network) while another RA procedure is already ongoing,it may be up to the UE implementation whether to continue with theongoing procedure or start with the new procedure. The eNB may initiatethe RA procedure via a PDCCH order for an activated SCell. This PDCCHorder may be sent on the scheduling cell of this SCell. When crosscarrier scheduling is configured for a cell, the scheduling cell may bedifferent than the cell that is employed for preamble transmission, andthe PDCCH order may include the SCell index. At least a non-contentionbased RA procedure may be supported for SCell(s) assigned to sTAG(s).Upon new UL data arrival, the UE may not trigger an RA procedure on anSCell. PDCCH order for preamble transmission may be sent on a differentserving cell than the SCell in which the preamble is sent. TA groupingmay be performed without requiring any additional UE assistedinformation.

FIG. 7 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention. eNB transmits an activation command 600 to activate an SCell.A preamble 602 (Msg1) may be sent by a UE in response to the PDCCH order601 on an SCell belonging to an sTAG. In an example embodiment, preambletransmission for SCells may be controlled by the network using PDCCHformat 1A. Msg2 message 603 (RAR: random access response) in response tothe preamble transmission on SCell may be addressed to RA-CRNTI in PCellcommon search space (CSS). Uplink packets 604 may be transmitted on theSCell, in which the preamble was transmitted.

According to some of the various aspects of embodiments, initial timingalignment may be achieved through a random access procedure. This mayinvolve the UE transmitting a random access preamble and the eNBresponding to an initial TA command NTA (amount of time alignment)within the random access response window. The start of the random accesspreamble may be aligned with the start of the corresponding uplinksubframe at the UE assuming NTA=0. The eNB may estimate the uplinktiming from the random access preamble transmitted by the UE. The TAcommand may be derived by the eNB based on the estimation of thedifference between the desired UL timing and the actual UL timing. TheUE may determine the initial uplink transmission timing relative to thecorresponding downlink of the sTAG on which the preamble is transmitted.

PDCCH order may be used to trigger RACH for an activated SCell. For anewly configured SCell or a configured but deactivated SCell, eNB mayneed to firstly activate the corresponding SCell and then trigger a RAon it. In an example embodiment, with no retransmission of anactivation/deactivation command, activation of an SCell may need atleast 8 ms, which may be an extra delay for UE to acquire the valid TAvalue on an SCell compared to the procedure on an already activatedSCell. For a newly configured SCell or a deactivated SCell, 8 msec maybe required for SCell activation, and at least 6 msec may be requiredfor preamble transmission, and at least 4 msec may be required toreceive the random access response. At least 18 ms may be required for aUE to get a valid TA. The possible delay caused by retransmission orother configured parameters may need to be considered (e.g. the possibleretransmission of an activation/deactivation command, and/or the timegap between when a RA is triggered and when a preamble is transmitted(equal or larger than 6 msec)). The RAR may be transmitted within theRAR window (for example, 2 msec, 10 msec, 50 msec), and possibleretransmission of the preamble may be considered. The delay for such acase may be more than 20 msec or even 30 msec if retransmissions areconsidered.

A base station may communicate with a mix of wireless devices. Wirelessdevices may support multiple technologies, or multiple releases of thesame technology, have some specific capability depending on the wirelessdevice category and/or capability. A base station may comprise multiplesectors. When this disclosure refers to a base station communicatingwith a plurality of wireless devices, this disclosure may refer to asubset of the total wireless devices in the coverage area. Thisdisclosure may refer to, for example, a plurality of wireless devices ofa given LTE release with a given capability and in a given sector of thebase station. The plurality of wireless devices in this disclosure mayrefer to a selected plurality of wireless devices, and/or a subset oftotal wireless devices in the coverage area, which perform according tothe disclosed methods, and/or the like. There may be many wirelessdevices in the coverage area that may not comply with the disclosedmethods, for example, because those wireless devices perform based onolder releases of LTE technology. A time alignment command MAC controlelement may be a unicast MAC command transmitted to a wireless device. Awireless device may receive its own time alignment commands.

According to some of the various aspects of various embodiments, thebase station or wireless device may group cells into a plurality of cellgroups. The term “cell group” may refer to a timing advance group (TAG)or a timing alignment group or a time alignment group. A cell group mayinclude at least one cell. A MAC TA command may correspond to a TAG. Agroup may explicitly or implicitly be identified by a TAG index. Cellsin the same band may belong to the same cell group. A first cell's frametiming may be tied to a second cell's frame timing in a TAG. When a timealignment command is received for the second cell, the frame timing ofboth first cell and second cell may be adjusted. Base station(s) mayprovide TAG configuration information to the wireless device(s) by RRCconfiguration message(s).

According to some of the various aspects of some embodiments, the numberof time alignment commands transmitted by the base station to a wirelessdevice in a given period may depend, at least in part, on manyparameters including at least one of: a) the speed that the wirelessdevice moves in the coverage area, b) the direction that the wirelessdevice moves in the coverage area, c) the coverage radius, and/or d) thenumber of active wireless devices in the coverage area. A base stationmay transmit at least two types of time alignment commands. A first typecommand may be transmitted to a first category of wireless devices. Thefirst category may include devices compatible with at least release 8,9, or 10 of the LTE standard. A second type command may be transmittedto a second category of devices. The second category may include deviceswith multi-time alignment group (MTG) capability and compatible withrelease 11 or beyond of the LTE standard. The time alignment may betransmitted to wireless devices that are in connected mode and areapplicable to active cells.

A UE may transmit a Scheduling Request (SR) and/or a buffer statusreport (BSR) due to uplink data arrival in the UE. A UE may transmit ascheduling request on PUCCH when the UE has data for uplink transmissionand UE do not have uplink grants for transmission of a buffer statusreport. The UE may receive uplink grant in response to a SR. A basestation scheduler may also provide an uplink grant to a UE for someother reasons, for example, based on a previous BSR. The UE may transmita MAC BSR in the uplink resources identified in an uplink grant toinform the base station about the size of the uplink transmissionbuffer(s). A UE BSR may be transmitted in an uplink resource identifiedin a received uplink grant. BSR indicates the amount of data in one ormore logical channel buffers. Base station may determine the radioresources required for the UE in the uplink employing the received BSRand other parameters, e.g. link quality, interference, UE category,and/or the like. If the base station determines that radio resources ofa first SCell which is uplink unsynchronized is required (the SCell maybe in-active or may not be even configured yet), the base station maytrigger an sTAG sync process to uplink synchronize the sTAG and thefirst SCell associated with the sTAG. The SCell should be in configured(e.g. using RRC messages) and be in active state (e.g. using MACactivate commands). An SCell is considered out-of-sync if it belongs toor will belong to (after RRC configuration) to an out-of-sync sTAG.

The sTAG sync process may also selectively be started by the basestation if a GBR bit rate bearer with required uplink resources has beenestablished. The Base station may determine the radio resources requiredfor the UE in the uplink employing the received bit rate, QoS andpriority requirements of the GBR bearer and other parameters, e.g. linkquality, interference, UE category, and/or the like. If the base stationdetermines that radio resources of a first SCell which is uplinkunsynchronized is required (the SCell may be in-active or may not beeven configured yet), the base station may trigger an sTAG sync processto uplink synchronize the sTAG and the first SCell associated with thesTAG. The SCell should be in configured (e.g. using RRC messages) and bein active state (e.g. using MAC activate commands) before uplinktransmission starts.

eNB may select to synchronize the sTAG and then activate/configure theSCell. eNB may select to first configure/activate SCell and then touplink synchronize it. For example, if an SCell is added and assigned toa synchronized sTAG, it will be synchronize upon its(re)configuration/addition. In another example, the SCell may beconfigured, then the sTAG may be synchronized using another SCell in thesTAG, and then the SCell may be activated. In another example, the SCellmay be configured/activated, and then sTAG synchronization may start.Different embodiments with different orders in tasks may be implemented.Random access process for an SCell can only be initiated on configuredand active SCells assigned to an sTAG.

In an example embodiment, in the sTAG sync process the base station maytrigger random access preamble transmission on an SCell of the sTAG thatthe SCell belongs, or on the first SCell in which its uplink resourcesare required. In this example, the first SCell belongs to an sTAG whichis uplink out-of-sync. In response to receiving a BSR and/or GBR bearerestablishment, the eNB may, selectively and depending on a plurality ofcriteria, transmit a PDCCH order to the UE and may cause the UE to starta RA procedure on an SCell in the sTAG (in case of carrier aggregation).A PDCCH order may be triggered by the BSR reception due to the UL dataarrival in the UE or by the establishment of GBR bearer with uplinkresource requirements. Preamble transmission may be triggered in thecase of UL data arrival, meaning that preamble transmission may betriggered by the BSR reception in the eNB and/or establishment of a nonGBR bearer with uplink data. Upon new UL data arrival, the UE may nottrigger an RA procedure on an SCell. The eNB may, selectively, triggerthe RA procedure based on the BSR reception due to UL data arrival inthe UE. eNB may consider many parameters in triggering an RA on anSCell. For example, parameters may include current eNB load, UE buffersize(s) in BSR report(s), UE category, UE capability, QoS requirements,GBR bearer requirements and/or the like. UE may determine that radioresources of the out-of-sync SCell may be required for uplink datatransmission.

In a second embodiment, in the sTAG sync process base station maytransmit a MAC timing advance command with a TAG index of theout-of-sync sTAG. The UE may use an stored value of N_TA for the out ofsync sTAG and apply the timing advance value in the MAC timing advancecommand to the stored N_TA of the sTAG. A UE may store or maintains N_TA(current timing advance value of an sTAG) upon expiry of associated timeAlignment Timer of the sTAG. The UE may apply the received timingadvance command MAC control element and starts associated time AlignmentTimer. This process may practically put the sTAG in an in-sync state.The base station may transmit one or more MAC timing advance commandsupon receiving uplink packets from the UE on the sTAG to align UE uplinktransmissions in the sTAG. It is up to eNB to select the first or secondembodiment for synchronizing the uplink of first SCell. For example, theeNB may operate in the second embodiment, if the SCell has not beenin-sync for a long time, or the sTAG has not been in-Sync since it hasbeen configured. In another example, the eNB may operate in the firstembodiment if the sTAG has recently entered an out-of-sync state. Inanother example, the eNB may operate in the second embodiment if theeNB-UE distance is relatively short, for example in the range of tens orhundreds of meters.

The mapping of a serving cell to a TAG may be configured by the servingeNB with RRC signaling. The mechanism for TAG configuration andreconfiguration may be based on RRC signalling. When needed, the mappingbetween an SCell and a TA group may be reconfigured with RRC signaling.In an example implementation, the mapping between an SCell and a TAG maynot be reconfigured with RRC while the SCell is configured. For exampleif there is a need to move an SCell from an sTAG to a pTAG, at least oneRRC message, for example, at least one RRC reconfiguration message, maybe send to the UE to reconfigure TAG configurations. The PCell may notchange its TA group and may always be a member of the pTAG.

According to some of the various aspects of embodiments, when an eNBperforms SCell addition configuration, the related TAG configuration maybe configured for the SCell. In an example embodiment, eNB may modifythe TAG configuration of an SCell by removing (releasing) the SCell andadding a new SCell (with the same physical cell ID and frequency) withan updated TAG ID. The new SCell with the updated TAG ID may beinitially inactive subsequent to joining the updated TAG ID. eNB mayactivate the updated new SCell and then start scheduling packets on theactivated SCell. In an example implementation, it may not be possible tochange the TAG associated with an SCell, but rather, the SCell may needto be removed and a new SCell may need to be added with another TAG.This may not require employing mobilityControlInfo in the RRCreconfiguration message.

An eNB may perform initial configuration based on initial configurationparameters received from a network node (for example a managementplatform), an initial eNB configuration, a UE location, a UE type, UECSI feedback, UE uplink transmissions (for example, data, SRS, and/orthe like), a combination of the above, and/or the like. For example,initial configuration may be based on UE channel state measurements. Forexample, depending on the signal strength received from a UE on variousSCells downlink carrier or by determination of UE being in a repeatercoverage area, or a combination of both, an eNB may determine theinitial configuration of sTAGs and membership of SCells to sTAGs.

In an example implementation, the TA value of a serving cell may change,for example due to UE's mobility from a macro-cell to a repeater or anRRH (remote radio head) coverage area. The signal delay for that SCellmay become different from the original value and different from otherserving cells in the same TAG. In this scenario, eNB may relocate thisTA-changed serving cell to another existing TAG. Or alternatively, theeNB may create a new TAG for the SCell based on the updated TA value.The TA value may be derived, for example, through eNB measurement(s) ofsignal reception timing, a RA mechanism, or other standard orproprietary processes. An eNB may realize that the TA value of a servingcell is no longer consistent with its current TAG. There may be manyother scenarios which require eNB to reconfigure TAGs. Duringreconfiguration, the eNB may need to move the reference SCell belongingto an sTAG to another TAG. In this scenario, the sTAG would require anew reference SCell. In an example embodiment, the UE may select anactive SCell in the sTAG as the reference timing SCell.

eNB may consider UE's capability in configuring multiple TAGs for a UE.UE may be configured with a configuration that is compatible with UEcapability. Multiple TAG capability may be an optional feature and perband combination. Multiple TAG capability may be introduced. UE maytransmit its multiple TAG capability to eNB via an RRC message and eNBmay consider UE capability in configuring TAG configuration(s).

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells). As part of the procedure, NASdedicated information may be transferred from E-UTRAN to the UE. If thereceived RRC Connection Reconfiguration message includes thesCellToReleaseList, the UE may perform an SCell release. If the receivedRRC Connection Reconfiguration message includes the sCellToAddModList,the UE may perform SCell additions or modification.

When a UE receives an sCellToAddModList in an RRC reconfigurationmessage, the UE may process the content of the message. The UE may, foran sCellIndex value included in the sCellToAddModList that is not partof the current UE configuration (SCell addition), add the SCellcorresponding to the cellIdentification in accordance with the receivedradioResourceConfigCommonSCell (SCell common configuration parameters)and radioResourceConfigDedicatedSCell (SCell dedicated configurationparameters). The UE may configure lower layers to consider the SCell tobe in a deactivated state. The UE may, for a sCellIndex value includedin the sCellToAddModList that is part of the current UE configuration(SCell modification), modify the SCell configuration in accordance withthe received radioResourceConfigDedicatedSCell.

According to some of the various aspects of embodiments, commonparameters may comprise downlink common parameters and uplink commonparameters. Examples of downlink common parameters include: downlinkbandwidth, antennaInfoCommon, mbsfn-SubframeConfigList, phich-Config,pdsch-ConfigCommon, and tdd-Config. Examples of uplink common parametersinclude: ul-CarrierFreq, ul-Bandwidth, p-Max,uplinkPowerControlCommonSCell, soundingRS-UL-ConfigCommon,ul-CyclicPrefixLength, prach-ConfigSCell (TDD), and pusch-ConfigCommon.Dedicated parameters may comprise downlink dedicated parameters anduplink dedicated parameters. Examples of downlink dedicated parametersinclude AntennaInfoDedicated, CrossCarrierSchedulingConfig,csi-RS-Config, pdsch-ConfigDedicated. Examples of uplink dedicatedparameters include antennaInfoUL, pusch-ConfigDedicatedSCell,uplinkPowerControlDedicatedSCell, cqi-ReportConfigSCell,soundingRS-UL-ConfigDedicated, soundingRS-UL-ConfigDedicated,soundingRS-UL-ConfigDedicatedAperiodic, and pathlossReferenceLinking.The names of these variables and example definition(s) and format forthese variables may be found in releases of LTE RRC standarddocumentation.

In an example embodiment, SCell TAG configuration(s) (e.g. TAG IDassignment) may be included in sCellToAddModList or one of the IEs insCellToAddModList. A TAG ID may be included in the TAG configuration ofa cell. The TA group may be configured when an SCell is added. Thus theconfiguration of a TA group may be seen as part of the SCelladdition/modification. A dedicated parameter in SCell dedicatedparameters may include the TAG ID of the SCell if the SCell belongs toan sTAG. If a dedicated TAG id parameter is not included in dedicatedradio resource configuration of an SCell, it may be assumed that theSCell is assigned to the pTAG. This may be an implicit assignment of theSCell to pTAG. According to some of the various aspects of embodiments,some of the TAG configuration parameters may be included in commonconfiguration parameters and some other TAG configuration parameters maybe included in dedicated configuration parameters. SCellToAddModListtransmitted to a UE may comprise one or more of: an sCell Index, aphysical Cell Id, a downlink Carrier Frequency, aradioResourceConfigCommonSCell, and a radioResourceConfigDedicatedSCell.radioResourceConfigDedicatedSCell IE in sCellToAddModList transmitted toa UE (in RRC message(s)) may comprise the TAG ID that the SCell belongsto. A TA group configuration may be UE-specific (a dedicatedconfiguration parameter). The identity or index of a TA group which anSCell belongs to, a TA group identity (TAG ID), may be assigned to aSCell employing an dedicated parameter inradioResourceConfigDedicatedSCell. When an SCell is released, the TAGassignment of the SCell may also be released. eNB may not be needed toinclude TAG ID in sCellToReleaseList. Each Cell may be assigned a TAG ID(implicitly or explicitly). If an SCell is not assigned a TAG ID, theSCell may be considered belonging to the pTAG by default. Implicitassignment of SCells to pTAG may reduce the signaling overhead. It isexpected that in many operating scenarios, sTAGs are not configured, andtherefore transmission of pTAG index for the configured SCells isavoided. This may increase spectral efficiency and would reducesignaling overhead.

A TAG ID may be UE specific, and each UE may have its own TAGconfiguration. For example, a given SCell may be a part of the pTAG inone UE and a part of an sTAG in another UE. In this embodiment, theSCell configuration may include TAG Index. Assignment of an SCell to ansTAG may be UE specific, and may be different for different UEsconnected to the same eNB. For example, a UE in the coverage of arepeater connected to the eNB may have a different sTAG configurationthan a UE which is directly connected to the same eNB.

According to some of the various aspects of embodiments,MAC-Config-Dedicated parameter in an RRC connection reconfigurationmessage may include a dedicated TAT parameter for each of the timealignment groups configured in the UE. In this example embodiment, a TATmay be included in MAC Dedicated parameters. If TAT for an sTAG isreceived in MAC-Dedicated parameters, the UE may consider the dedicatedparameter. For an SCell in an sTAG, the UE may not consider timealignment timer in the SIB parameter received from an eNB, instead theUE may consider the time alignment configuration parameter in theMAC-Dedicated parameters. Different UEs may be required to be configuredwith different TAT values in an optimized network operation. UE TATvalue may be optimized depending on eNB-UE distance, UE speed, UEcategory, and/or the like. Therefore, it is not recommended to use acommon variable for time alignment timer of secondary cell groups.

The TA maintenance for PCell may follow Rel-10 principles. If an SCellapplying the TA of PCell is added, the Rel-10 procedures may be reused.In one example embodiment, there is no need to explicitly assign a TAGID for cells in the pTAG. SCells configured with the pTAG may be groupedimplicitly and a TAG ID for pTAG may not be needed or a TAG ID may beassigned implicitly by default (for example, TAGID: 0). TAG identity maybe regarded as zero if the TAG identity field is absent in SCelldedicated parameters upon SCell addition. If an SCell is not configuredwith a TAG ID, it may apply that the SCell belongs to the pTAG.

According to some of the various aspects of embodiments, sTAGconfigurations may be released upon re-establishment or handover. TAGrelated configuration may include TAG ID, TAG-specific TAT, and/or theserving cells associated with it. In an example embodiment MAC dedicatedparameters IE may include a TAG configuration information elementcomprising a sequence of one or more TAG ID and TAT for configured TAGs.In an example embodiment the TAG configuration information element mayalso comprise the list of SCells belonging to the TAG. The associationbetween SCells with TAG IDs may be included in SCell configuration IEparameters, or may be included in TAG configuration information element.

The parameters related to SCell random access channel may be common toall UEs. For example PRACH configuration (RACH resources, configurationparameters, RAR window) for the SCell may be common to all UEs. RACHresource parameters may include prach-configuration index, and/orprach-frequency offset. SCell RACH common configuration parameters mayalso include power: power ramping parameter(s) for preambletransmission; and max number of preamble transmission parameter. It ismore efficient to use common parameters for RACH configuration, sincedifferent UEs will share the same random access channel. Using dedicatedparameters for SCell RACH configuration is not preferred since it willincrease the size of the radio resources required for random accessprocess, and may reduce spectral efficiency.

In an example implementation, TAT of an sTAG may not be running when thelast SCell of the group is removed from the TA group. The eNB may removesTAG when removing the last SCell from the sTAG. When sTAG is removedthe TAT for sTAG may be stopped and the NTA value may be discarded.According to some of the various aspects of embodiments, sTAG TATconfiguration may be released when no SCell is configured in the sTAG.When sTAG is released, then TAT is also released/de-configured (e.g.this may be achieved by de-configuring the timer). Upon sTAG depletion,the TAT may be de-configured by the eNB, which may implicitly stop theTAT of this group at the same time. If an sTAG is empty, the same RRCmessage may remove the sTAG and TAT and a removed sTAG may bereleased/de-configured. In another example embodiment, TAT may bestopped but a TAT entity may be maintained.

eNB may transmit at least one RRC message to configure PCell, SCell(s)and RACH, and TAG configuration parameters. MAC-MainConfig may include atimeAlignmentTimerDedicated IE to indicate time alignment timer valuefor the pTAG. MAC-MainConfig may further include an IE including asequence of at least one (sTAG ID, and TAT value) to configure timealignment timer values for sTAGs. In an example, a first RRC message mayconfigure TAT value for pTAG, a second RRC message may configure TATvalue for sTAG1, and a third RRC message may configure TAT value forsTAG2. There is no need to include all the TAT configurations in asingle RRC message. The IE including a sequence of at least one (sTAGID, and TAT) value may also be used to update the TAT value of anexisting sTAG to an updated TAT value. The at least one RRC message mayalso include sCellToAddModList including at least one SCellconfiguration parameters. The radioResourceConfigDedicatedSCell(dedicated radio configuration IEs) in sCellToAddModList may include anSCell MAC configuration comprising TAG ID for the corresponding SCelladded or modified. The radioResourceConfigDedicatedSCell may alsoinclude pathloss reference configuration for an SCell. If TAG ID is notincluded in SCell configuration, the SCell is assigned to the pTAG. Inother word, a TAG ID may not be included inradioResourceConfigDedicatedSCell for SCells assigned to pTAG. TheradioResourceConfigCommonSCell (common radio configuration IEs) insCellToAddModList may include RACH resource configuration parameters,preamble transmission power control parameters, and other preambletransmission parameter(s). At the least one RRC message configuresPCell, SCell, RACH resources, and/or SRS transmissions and may assigneach SCell to an sTAG (implicitly or explicitly). PCell is alwaysassigned to the pTAG.

The pathloss reference IE (pathlossReferenceLinking) inradioResourceConfigDedicatedSCell may indicate whether the UE shallapply as pathloss reference either: the downlink of the PCell, or of theSIB2 downlink of the SCell that corresponds with the configured uplink.For SCells part of a secondary TAG eNB may only configure the pathlossreference to SIB2 downlink of the SCell that corresponds with theconfigured uplink. If a serving cell belongs to a TAG containing theprimary cell then, for the uplink of the primary cell, the primary cellis used as the reference serving cell for determining reference SignalPower. For the uplink of the secondary cell, the serving cell configuredby the RRC parameter pathloss Reference Linking IE is used as thereference serving cell for determining reference signal power. If aserving cell belongs to an sTAG then the serving cell is used as thereference serving cell for determining reference signal power.

According to some of the various aspects of embodiments, a base stationmay transmit at least one control message to a wireless device in aplurality of wireless devices. The at least one control message is forexample, RRC connection reconfiguration message, RRC connectionestablishment message, RRC connection re-establishment message, and/orother control messages configuring or reconfiguring radio interface,and/or the like. The at least one control message may be configured tocause, in the wireless device, configuration of at least:

a) a plurality of cells. Each cell may comprise a downlink carrier andzero or one uplink carrier. The configuration may assign a cell groupindex to a cell in the plurality of cells. The cell group index mayidentify one of a plurality of cell groups. A cell group in theplurality of cell groups may comprise a subset of the plurality ofcells. The subset may comprise a reference cell with a referencedownlink carrier and a reference uplink carrier. Uplink transmissions bythe wireless device in the cell group may employ a synchronizationsignal transmitted on the reference downlink carrier as timingreference.

b) a plurality of MAC dedicated parameters comprising a sequence of atleast one element. An element in the sequence may comprises a timealignment timer value and a secondary time alignment group index. pTAGtime alignment timer value may be included as a dedicated IE in MAC mainconfiguration parameter (a dedicated IE). Each time alignment timervalue being selected, by the base station, from a finite set ofpredetermined values. The time alignment timer value in the sequence maybe associated with a cell group index that is specified in the sameelement. In an example embodiment, the element may also comprise thelist of cell indexes associated with the time alignment group index.

c) a time alignment timer for each cell group in the plurality of cellgroups.

The base station may transmit a plurality of timing advance commands.Each timing advance command may comprise: a time adjustment value, and acell group index. A time alignment timer may start or may restart whenthe wireless device receives a timing advance command to adjust uplinktransmission timing on a cell group identified by the cell group index.The cell group may be considered out-of-sync, by the wireless device,when the associated time alignment timer expires or is not running. Thecell group may be considered in-sync when the associated time alignmenttimer is running.

The timing advance command may causes substantial alignment of receptiontiming of uplink signals in frames and subframes of all activated uplinkcarriers in the cell group at the base station. The time alignment timervalue may be configured as one of a finite set of predetermined values.For example, the finite set of predetermined values may be eight. Eachtime alignment timer value may be encoded employing three bits. TAG TATmay be a dedicated time alignment timer value and is transmitted by thebase station to the wireless device. TAG TAT may be configured to causeconfiguration of time alignment timer value for each time alignmentgroup. The IE TAG TAT may be used to control how long the UE isconsidered uplink time aligned. It corresponds to the timer for timealignment for each cell group. Its value may be in number of subframes.For example, value sf500 corresponds to 500 subframes, sf750 correspondsto 750 subframes and so on. An uplink time alignment is common for allserving cells belonging to the same cell group. In an exampleembodiment, the IE TAG TAT may be defined as: TAG TAT::=SEQUENCE{TAG ID,ENUMERATED {sf500, sf750, sf1280, sf1920, sf2560, sf5120, sf10240,infinity}. Time alignment timer for pTAG may be indicated in a separateIE and may not be included in the sequence.

In an example, TimeAlignmentTimerDedicated IE may be sf500, and then TAGTAT may be {1, sf500; 2, sf2560; 3, sf500}. In the example, timealignment timer for the pTAG is configured separately and is notincluded in the sequence. In the examples, TAG0 (pTAG) time alignmenttimer value is 500 subframes (500 m-sec), TAG1 (sTAG) time alignmenttimer value is 500 subframes, TAG2 time alignment timer value is 2560subframes, and TAGS time alignment timer value is 500 subframes. This isfor example purposes only. In this example a TAG may take one of 8predefined values. In a different embodiment, the enumerated valuescould take other values. The size of the sequence is 3 in the firstexample and 4 in the second example. In another example embodiment, thesize could be 2, 3, equal to the size of configured TAGs in the wirelessdevice, and/or the like.

FIG. 9 is an example physical random access channel (PRACH)configuration in a primary TAG (pTAG) and a secondary TAG (sTAG) as peran aspect of an embodiment of the present invention. As shown in theexample, PRACH resources are configured for the PCell in pTAG and SCell2and SCell3 in sTAG. SCell1 and SCell4 are not configured with PRACHresources. This is an example and other configurations are alsopossible. In an example embodiment, no SCell in pTAG is configured withPRACH resources. In another example embodiment, PRACH resources for anSCell in pTAG may be configured, but eNB is not configured to trigger apreamble transmission on PRACH resources of an SCell in pTAG. Basically,PRACH resources in SCells in pTAG cannot be used for preambletransmissions by a UE.

According to some of the various aspects of embodiments, a UE may selectone active SCell DL in a secondary TAG as the DL timing reference cellfor the secondary TAG. This may reduce signalling overhead or complexityof implementation and/or increase efficiency. For a UE, an sTAG may haveone timing reference cell at a given time. In an example embodiment, theactive SCell with the highest signal quality may be selected as thetiming reference SCell by the UE. In another example embodiment, DLtiming reference cell for an sTAG may be the SCell DL SIB2-linked withthe SCell UL where RACH was performed. For preamble transmission, theSIB2 linked DL of the cell which the preamble is sent may be used as DLtiming reference. In an example embodiment, UE may autonomously select adownlink carrier in an active cell in the sTAG as the reference SCell.When TA command is received in RAR or MAC CE, the UE may apply the TAvalue to current UL timing of the corresponding TAG.

One timing reference SCell may be employed in an sTAG, the timingalignment value in RAR (random access response) or TAC (time alignmentcommand) may be applied to all active SCell(s) in the same sTAG. Thus,the UE may select the most suitable SCell for timing reference dependingon different circumstances. For example, the SCell which has a bettersignal quality may be selected as timing reference cell, since bettersignal quality may provide a more reliable performance and thus reducethe need of re-configuring the timing reference cell. Channel quality ofan SCell in an sTAG may be considered for initial SCell timing referenceand for reselecting timing reference cell. UE may change the timingreference when it is necessary.

In an example embodiment, the SCell served as the timing reference cellin sTAG may be deactivated in some cases. For a UE, eNB may keep a stateof an SCell as active or inactive. In a UE, when an SCell is inactive,the UE may switch off some parts of the receiver and/or transmittercorresponding to the SCell. This act may reduce battery powerconsumption in the UE. In another example embodiment, the referenceSCell in an sTAG may be released by the serving eNB. The timingreference cell may be changed to another active SCell in the sTAG formaintaining UL timing alignment for SCells in the same sTAG. Change oftiming reference cell in an sTAG may be supported. The reference cellmay also be changed for other reasons such as coverage quality, PRACHfailure, Reference SCell release, subscriber mobility, a combination ofthe above, and/or the like. These scenarios may apply to cases wheretime alignment is running. If the time alignment is not running and thesTAG is not time aligned, then there is no uplink synchronization and UEmay not use any reference SCell for uplink synchronization. In anexample embodiment, the UE may autonomously change the timing referenceSCell to another active SCell in the sTAG without informing the servingbase station. The UE may not inform the base station about a change inthe reference SCell, this process avoids additional signaling from a UEto the eNB and may increase radio resource efficiency. This processoptimizes reference cell selection by the UE so that the UE can select asuitable SCell as the reference, without adding complexity in thenetwork and without introducing additional signaling overhead.

According to some of the various aspects of embodiments, UE mayautonomously select another reference SCell when the reference SCellbecomes deactivated. Since the timing reference is used to derive the ULtransmission timing at the UE, there is a need for the UE to select adownlink SCell as the timing reference. The UE may autonomously reselectanother activated SCell in the sTAG as the reference when needed. Timingreference for uplink transmission on SCell may be reselected to the DLtiming of any activated SCell of the same sTAG when needed. Anyactivated SCell in the sTAG may be chosen by the UE autonomously as thetiming reference for this sTAG. For example, initially downlink SCell inwhich RA is transmitted may be used as a timing reference and then theUE may use another SCell as the timing reference, when the referenceSCell needs to be changed.

FIG. 10 is an example flow diagram illustrating timing reference changeas per an aspect of an embodiment of the present invention. At 1000, awireless device may receive control message(s) from a base station. Thecontrol message(s) may cause in the wireless device configuration of aplurality of cells. The plurality of cells may comprise a primary celland a plurality of secondary cells.

According to some of the various embodiments, the control message(s) mayalso cause in the wireless device configuration of a deactivation timerfor each secondary cell in plurality of secondary cells. Thedeactivation timer may correspond to a secondary cell restarting inresponse to a packet transmission on the secondary cell. An RRC messagemay comprise MAC main configuration parameter comprising a deactivationtimer value. The activation timer value may be applicable todeactivation timers of each of the secondary cells. The correspondingsecondary cell may be deactivated in the wireless device in response tothe deactivation timer expiring. The deactivation timer may correspondto secondary cell restarts in response to receiving an activationcommand for the secondary cell.

According to some of the various embodiments, the control message(s) mayalso cause in the wireless device assignment of each of the plurality ofsecondary cells to a cell group in a plurality of cell groups. Theplurality of cell groups may comprise a primary cell group and asecondary cell group. The primary cell group may comprise a first subsetof the plurality of cells. The first subset may comprise the primarycell. Uplink transmissions by the wireless device in the primary cellgroup may employ a first synchronization signal transmitted on theprimary cell as a primary timing reference. The secondary cell group maycomprise a second subset of the plurality of secondary cells. The secondsubset may comprise a reference secondary cell.

According to some of the various embodiments, the control message(s) maycomprise a plurality of media access control dedicated parameterscomprising a deactivation timer value. The deactivation timer value maybe employed for each of the deactivation timers for the plurality ofsecondary cells.

According to some of the various embodiments, first uplink signals inthe secondary cell group may be transmitted by the wireless device at1002. The transmission may employ a synchronization signal on thereference secondary cell as a secondary timing reference. The referencesecondary cell may be an activated cell in the secondary cell group.

According to some of the various embodiments, at 1007, the wirelessdevice may autonomously select a new activated secondary cell in thesecondary cell group as the secondary timing reference if the referencesecondary cell is deactivated in the wireless device; and at least onesecondary cell in the secondary cell group is active in the wirelessdevice. The autonomous selection may be performed by the wireless devicewithout the wireless device informing the base station.

According to some of the various embodiments, second uplink signals maybe transmitted in the secondary cell group by the wireless device at1009. The transmission may employ a second synchronization signal on thenew activated secondary cell as the secondary timing reference.

The wireless device may receive a control command configured to causetransmission of a random access preamble on random access resources ofthe reference secondary cell in the secondary cell group. The wirelessdevice may receive a random access response on a primary cell in theprimary cell group. The random access response may comprise a timingadvance command for the secondary cell group. The base station mayreceive the random access preamble on the random access resources.Transmission timing of the random access preamble may be determined, atleast in part, employing the synchronization signal transmitted on thereference secondary cell. The control message(s) may cause configurationof the random access resources.

According to some of the various embodiments, the base station maytransmit at least one timing advance command to the wireless device. Thetiming advance command may comprise: a time adjustment value; and anindex identifying the secondary cell group. The timing advancecommand(s) may be configured to cause substantial alignment of receptiontiming of the uplink signals in frames and subframes of the secondarycell group at the base station.

According to some of the various embodiments, the wireless device may beassigned a plurality of media access control dedicated parameters by theconfiguration. The plurality of media access control dedicatedparameters may comprise a plurality of time alignment timer values. Eachof the plurality of time alignment timer values may be associated with aunique cell group in the wireless device.

Embodiments may vary. For example, according to some of the variousembodiments, the control message(s) may cause in said wireless deviceassignment of each of the plurality of secondary cells to a cell groupin a plurality of cell groups. The plurality of cell groups may comprisea secondary cell group comprising a subset of the plurality of secondarycells. The control message(s) may comprises at least one cell add-modifyinformation element. Each of the cell add-modify information element(s)may comprise a first plurality of dedicated parameters in the pluralityof dedicated parameters. The first plurality of dedicated parameters maycomprise a first cell index for a first secondary cell in the secondarycell(s).

According to some of the various embodiments, the control message(s) maybe configured to further cause in the wireless device configuration of atime alignment timer for each of the plurality of cell groups. The timealignment timer may start or restart in response to the wireless devicereceiving a timing advance command to adjust uplink transmission timingof a commanded cell group in the plurality of cell groups.

According to some of the various embodiments, the wireless device maytransmit first uplink signals in the secondary cell group at 1002employing a synchronization signal on a reference secondary cell in thesecondary cell group as a timing reference. The reference secondary cellmay be an activated cell in the secondary cell group.

According to some of the various embodiments, the wireless device mayautonomously select a new activated secondary cell in the secondary cellgroup as the timing reference at 1007 if the reference secondary cell isdeactivated in the wireless device; and at least one secondary cell inthe secondary cell group is active in the wireless device. The selectionmay be performed autonomously by the wireless device without thewireless device informing the base station. According to some of thevarious embodiments, the wireless device may not monitor the referencesecondary cell when the reference secondary cell is deactivated.

At 1009, the wireless device may transmit second uplink signals in thesecondary cell group employing a third synchronization signal on the newactivated secondary cell as the timing reference. The wireless devicemay transmit second uplink signals in the secondary cell group employinga third synchronization signal on the new activated secondary cell asthe timing reference

According to some of the various embodiments, an activation command maybe received causing activation of the new secondary cell in the wirelessdevice.

According to some of the various embodiments, the base station maycomprise communication interface(s), processor(s), and memory. Thememory may store instructions. The processor(s) may execute theinstructions to cause actions described herein.

At 1000, a wireless device may receive control message(s) from a basestation. The control message(s) may cause in the wireless deviceconfiguration of a plurality of cells. The plurality of cells maycomprise a primary cell and a plurality of secondary cells.

According to some of the various embodiments, the control message(s) mayalso cause in the wireless device assignment of each of the plurality ofsecondary cells to a cell group in a plurality of cell groups. Theplurality of cell groups may comprise a primary cell group and asecondary cell group. The primary cell group may comprise a first subsetof the plurality of cells. The first subset may comprise the primarycell. Uplink transmissions by the wireless device in the primary cellgroup may employ a first synchronization signal transmitted on theprimary cell as a primary timing reference. The secondary cell group maycomprise a second subset of the plurality of secondary cells. The secondsubset may comprise a reference secondary cell.

According to some of the various embodiments, the control message(s) maycomprises a plurality of media access control dedicated parameterscomprising a deactivation timer value. The deactivation timer value maybe employed for each of the deactivation timers for the plurality ofsecondary cells. The control message(s) may cause configuration of therandom access resources. The control message(s) may be configured tomodify a radio bearer.

According to some of the various embodiments, first uplink signals inthe secondary cell group may be transmitted by the wireless device at1002. The transmission may employ a synchronization signal on thereference secondary cell as a secondary timing reference. The referencesecondary cell may be an activated cell in the secondary cell group.

According to some of the various embodiments, at 1007, the wirelessdevice may autonomously select (without the wireless device informingthe base station) a new activated secondary cell in the secondary cellgroup as the secondary timing reference. The new activated secondarycell may be different from the reference secondary cell.

According to some of the various embodiments, at 1009, second uplinksignals may be transmitted in the secondary cell group by the wirelessdevice employing a third synchronization signal on the new activatedsecondary cell as the secondary timing reference.

A deactivation timer corresponding to the secondary cell may restart inresponse to receiving an activation command for the secondary cell.

According to some of the various embodiments, a wireless device mayreceive control message(s) from a base station. The control message(s)may cause in the wireless device configuration of: a plurality of cellscomprising a primary cell and a plurality of secondary cells; and a cellgroup index for a secondary cell in the plurality of cells. The cellgroup index may identify one of a plurality of cell groups. Theplurality of cell groups may comprise a secondary cell group. Thesecondary cell group may comprise a subset of the plurality of secondarycells. First uplink signals may be transmitted in the secondary cellgroup by the wireless device employing a first synchronization signal ona reference secondary cell in the secondary cell group as a timingreference. The reference secondary cell may be an activated cell in thesecondary cell group. The wireless device may autonomously select(without the wireless device informing the base station) a new activatedsecondary cell in the secondary cell group as the timing reference. Thenew activated secondary cell may be different from the referencesecondary cell. Second uplink signals may be transmitting in thesecondary cell group by the wireless device employing a secondsynchronization signal on the new activated secondary cell as the timingreference.

According to some of the various aspects of embodiments, if the UE isconfigured with one or more SCells, the network may activate anddeactivate the configured SCells associated with a wireless device (UE).The PCell is always activated when UE is in RRC-Connected mode. Thenetwork may activate and deactivate the SCell(s) by sending theActivation/Deactivation MAC control element. Furthermore, a UE and eNBmay maintain an SCellDeactivationTimer timer per configured SCell andmay deactivate the associated SCell upon its expiry.sCellDeactivationTimer may be configured by RRC. The same initial timervalue may apply to instances of the sCellDeactivationTimer for SCells.The configured SCells may be initially deactivated upon addition and/orafter a handover. With the current sCellDeactivationTimer, SCell may bedeactivated during the PRACH process. Transmission of uplink preamble ona deactivated SCell may increase battery power consumption and UEcomplexity. If preamble is transmitted on a deactivated SCell, UE mayneed to turn on processing related to uplink transmission of the SCell.UE may not transmit data on a deactivated SCell and transmission ofpreamble may require special processing in the UE and may complicate UEimplementation. To address this issue, if the SCell is deactivatedduring an ongoing RA process on the SCell, for example because SCelldeactivation timer expires, the ongoing random access process on theSCell may be aborted. When an SCell is deactivated, the UE may stop alluplink transmissions (for the SCell) including uplink preamble. UE maynot transmit any uplink preamble when the SCell is deactivated. eNB mayavoid or reduce the probability of such a scenario, by keeping thecorresponding SCell activated during random access process. For example,eNB can explicitly activate the SCell before the random access processstarts. An eNB may initiate a random access process when there is enoughtime for performing the entire random access process. UE may start therandom access process on an activated SCell. But if the SCelldeactivation timer (of the SCell that is used for preamble transmission)expires during the random access process, the UE may deactivate theSCell and may abort the random access process and may not transmit apreamble in the uplink. This process may prevent a situation in whichthe UE may send uplink signals on a deactivated SCell. If an SCell in aUE is deactivated after a preamble transmission on the SCell and beforereceiving a random access response corresponding to the preambletransmission, the UE may abort the random access process. A randomaccess process on an SCell is initiated in a UE when the UE received aPDCCH order to transmit a preamble on the SCell. The random accessprocess is considered successfully completed when the UE successfullydecodes a corresponding RAR. If the SCell is deactivated after therandom access process is initiated and before the random access processis completed, then the UE may abort the random access process.

According to some of the various aspects of embodiments,sCellDeactivationTimer may be maintained in a way to reduce SCelldeactivation during the RA process. The UE may for a TTI and for aconfigured SCell, if the UE receives an Activation/Deactivation MACcontrol element in this TTI activating the SCell, the UE may in the TTIaccording to a predefined timing activate the SCell and start or restartthe sCellDeactivationTimer associated with the SCell. Activating anSCell may imply applying normal SCell operation including: SRStransmissions on the SCell (if the SCell is in sync), CQI/PMI/RI/PTIreporting for the SCell, PDCCH monitoring on the SCell, PDCCH monitoringfor the SCell. If the UE receives an Activation/Deactivation MAC controlelement in this TTI deactivating the SCell, or if thesCellDeactivationTimer associated with the activated SCell expires inthis TTI, in the TTI according to a predefined timing: deactivate theSCell, stop the sCellDeactivationTimer associated with the SCell, flushall HARQ buffers associated with the SCell.

If PDCCH on the activated SCell indicates an uplink grant or downlinkassignment, or if PDCCH on the Serving Cell scheduling the activatedSCell indicates an uplink grant or a downlink assignment for theactivated SCell, the UE may restart the sCellDeactivationTimerassociated with the SCell. If the SCell is deactivated, the UE may: nottransmit SRS on the SCell, not report CQI/PMI/RI/PTI for the SCell, nottransmit on UL-SCH on the SCell, not monitor the PDCCH on the SCell, notmonitor the PDCCH for the SCell, and/or not to transmit uplink preambleon the SCell.

In an example embodiment, an SCell deactivation timer of the SCell maybe restarted when the UE receives a PDCCH order to transmit uplinkpreamble on the SCell. The SCell deactivation timer of the Cell carryingPDCCH order may also be restarted in cross carrier schedulingconfiguration. In an example implementation, an SCell deactivation timerof the SCell may be restarted when the UE transmits a random accesspreamble on the uplink the SCell.

FIG. 11 is an example flow diagram illustrating an unsuccessful randomaccess process as per an aspect of an embodiment of the presentinvention. According to some of the various embodiments, a wirelessdevice may receive control message(s) from base station at 1100. Thecontrol message(s) may cause in the wireless device configuration of aplurality of cells comprising a primary cell and at least one secondarycell. The control message(s) may cause in the wireless deviceconfiguration of a deactivation timer for each secondary cell in thesecondary cell(s). The deactivation timer may correspond to a secondarycell restarting in response to a packet transmission on the secondarycell. The corresponding secondary cell may be deactivated in thewireless device in response to the deactivation timer expiring. Thedeactivation timer associated with the secondary cell may be restartedby the wireless device if a random access response with an uplink grantfor transmission on the secondary cell is received by the wirelessdevice from the base station. In an example embodiment, the deactivationtimer associated with the secondary cell may be restarted in response tothe wireless device receiving the control command. The deactivationtimer associated with a cell carrying the control command may berestarted if the cell is one of secondary cell(s). In an exampleimplementation, the deactivation timer may be restarted in the wirelessdevice when the wireless device transmits an uplink preamble.

According to some of the various embodiments, the control message(s) maycause in the wireless device assignment of each of the secondary cell(s)to a cell group in a plurality of cell groups. The plurality of cellgroups may comprise a primary cell group and a secondary cell group. Theprimary cell group may comprise a first subset of the plurality ofcells. The first subset may comprise the primary cell. Uplinktransmissions by the wireless device in the primary cell group mayemploy a first synchronization signal transmitted on the primary cell asa primary timing reference. The secondary cell group may comprise asecond subset of the secondary cell(s).

According to some of the various embodiments, the control message(s) maycause in the wireless device configuration of a time alignment timer forthe secondary cell group. The time alignment timer may start or restartin response to the wireless device receiving a timing advance command toadjust uplink transmission timing on the secondary cell group.

According to some of the various embodiments, the wireless device mayreceive a control command (also called PDDCH order) initiating a randomaccess process for a secondary cell in the secondary cell group in thewireless device at 1102. The control command may comprise a mask indexand the random access preamble identifier.

According to some of the various embodiments, the wireless device maytransmit a random access preamble on random access resources of thesecondary cell in response to receiving the control command at 1107.

According to some of the various embodiments, at 1109, the wirelessdevice may abort the random access process on the secondary cell if thesecondary cell is deactivated before the wireless device receives arandom access response for the random access preamble transmission. Adownlink control channel of the primary cell for the random accessresponse may be monitored after the random access preamble istransmitted. The random access response may comprise an identifier ofthe random access preamble. The random access response may betransmitted on the primary cell. The random access response may comprisea timing advance command for the secondary cell group.

According to some of the various embodiments, the wireless device maycomprise communication interface(s), processor(s), and memory. Thememory may store instructions. The processor(s) may execute theinstructions to cause actions described herein.

According to some of the various embodiments, the wireless device mayreceive at least control message(s) from a base station at 1100. Thecontrol message(s) may cause in the wireless device configuration of aplurality of cells comprising a primary cell and at least one secondarycell.

The control message(s) may cause in the wireless device configuration ofa deactivation timer for each secondary cell in the at least onesecondary cell, the deactivation timer may correspond to a secondarycell restarting in response to a packet transmission on the secondarycell. The corresponding secondary cell may be deactivated in thewireless device in response to the deactivation timer expiring.

The control message(s) may cause in the wireless device assignment ofeach of the secondary cell(s) to a cell group in a plurality of cellgroups. The plurality of cell groups may comprise a secondary cellgroup. The secondary cell group may comprise a second subset of thesecondary cell(s).

The control message(s) may cause in the wireless device configuration ofa time alignment timer for the secondary cell group. The time alignmenttimer may start or restart in response to the wireless device receivinga timing advance command to adjust uplink transmission timing on thesecondary cell group.

According to some of the various embodiments, the wireless device mayreceive a control command initiating a random access process for asecondary cell in the secondary cell group in the wireless device at1102. The control command may comprise a mask index and the randomaccess preamble identifier.

According to some of the various embodiments, the wireless device maytransmit a random access preamble on random access resources of thesecondary cell in response to receiving the control command at 1107. Thewireless device may monitor a downlink control channel of the primarycell for the random access response after transmitting the random accesspreamble. The wireless device may receive a random access response onthe primary cell. The random access response may comprise a timingadvance command for the secondary cell group. The random access responsemay comprise an identifier of the random access preamble.

According to some of the various embodiments, at 1109, the wirelessdevice may abort the random access process on the secondary cell if thesecondary cell is deactivated before the wireless device receives, onthe primary cell, a random access response for the random accesspreamble transmission.

FIG. 12 is an example flow diagram illustrating an unsuccessful randomaccess process as per an aspect of an embodiment of the presentinvention. A base station may transmit control message(s) to a wirelessdevice at 1200. The control message(s) may be configured to cause in thewireless device configuration of a plurality of cells comprising aprimary cell and at least one secondary cell.

According to some of the various embodiments, control message(s) may beconfigured to cause in the wireless device configuration of adeactivation timer for each secondary cell in secondary cell(s). Thedeactivation timer may correspond to a secondary cell restarting inresponse to a packet transmission on the secondary cell. Thecorresponding secondary cell may be deactivated in the wireless devicein response to the deactivation timer expiring.

According to some of the various embodiments, control message(s) may beconfigured to cause in the wireless device assignment of each of thesecondary cell(s) to a cell group in a plurality of cell groups. Theplurality of cell groups may comprise a secondary cell group. Thesecondary cell group may comprise a second subset of the secondarycell(s).

According to some of the various embodiments, control message(s) maycomprise a plurality of common parameters for the secondary cell. Theplurality of common parameters may comprise a plurality of random accessresource parameters identifying the random access resources and aplurality of power control parameters. Control message(s) may comprise aplurality of random access resource parameters. The plurality of randomaccess resource parameters may comprise: an index; a frequency offset;and a plurality of sequence parameters. Control message(s) may comprisea plurality of media access control dedicated parameters comprising aplurality of time alignment timer values. Each time alignment timervalue may be associated with a unique cell group in the wireless device.

According to some of the various embodiments, the base station maytransmit a control command initiating a random access process for asecondary cell in the secondary cell group at 1202. The control commandmay be configured to cause the wireless device to transmit a randomaccess preamble on random access resources of the secondary cell.

According to some of the various embodiments, at 1209, the base stationmay abort the random access process on the secondary cell if thesecondary cell is deactivated before the base station receives therandom access preamble on the random access resources.

The base station may receive the random access preamble from thewireless device. The base station may transmit a random access responsecomprising an uplink grant to the wireless device. The base station mayabort the random access process if the secondary cell is deactivatedbefore the base station receives an uplink packet from the wirelessdevice in response to the uplink grant.

According to some of the various aspects of embodiments, for pTAG, inthe case of RACH failure MAC and RRC layers perform certain functions.When the number of RA preamble transmissions reaches preambleTransMax,MAC layer in the UE may indicate Random Access problem to upper layers.UE may or may not continue RACH procedure, i.e. transmit the preamble.When RRC is informed of RACH failure from MAC, if neither T300,T301,T304nor T311 is running, the RRC layer may trigger reestablishment if AS(access stratum) security has been activated. Otherwise the UE maydirectly move to RRC_IDLE. The RACH procedure may be stopped and otherprocesses, for example, connection reestablishment, may start. For pTAG,when the number of RA preamble transmissions reaches preambleTransMax,the RACH procedure may be stopped by further RRC procedures. For pTAG,if random access fails, MAC may indicate a random access problem toupper layers and RRC may declare radio link failure and initiate RRCconnection re-establishment procedure.

The purpose of RRC connection re-establishment procedure may be tore-establish the RRC connection, which involves the resumption of SRB1operation, the re-activation of security and/or the configuration of thePCell. The UE may initiate the procedure when AS security has beenactivated. The UE may initiate the procedure upon detecting radio linkfailure. A UE in RRC_CONNECTED, for which security has been activated,may initiate the procedure in order to continue the RRC connection. Theconnection re-establishment may succeed if the concerned cell isprepared i.e. has a valid UE context. In case E-UTRAN accepts there-establishment, SRB1 (signalling radio bearer one) operation resumeswhile the operation of other radio bearers remains suspended. If ASsecurity has not been activated, the UE may not initiate the procedurebut instead may directly move to RRC_IDLE. E-UTRAN may apply RRCconnection re-establishment procedure to reconfigure SRB1 and to resumedata transfer for this RB (radio bearer) and/or to re-activate ASsecurity without changing algorithms.

If either T300,T301,T304 or T311 is running, when RACH problem isindicated from MAC to RRC, the RRC layer may do different handling ifcorresponding Timer expired. According to some of the various aspects ofembodiments, timer T300 starts by transmission of RRCConnectionRequestand stops by reception of RRCConnectionSetup or RRCConnectionRejectmessage, cell re-selection and upon abortion of connection establishmentby upper layers. If timer T300 expires, UE may reset MAC, release theMAC configuration and re-establish RLC for all RBs that are established.UE may also inform upper layers about the failure to establish the RRCconnection, upon which the procedure may end. Timer T301 starts bytransmission of RRCConnectionReestabilshmentRequest and stops byreception of RRCConnectionReestablishment orRRCConnectionReestablishmentReject message as well as when the selectedcell becomes unsuitable. After expiry UE may go to Go to RRC_IDLE. TimerT304 starts by reception of RRCConnectionReconfiguration messageincluding the MobilityControl Info or reception ofMobilityFromEUTRACommand message including CellChangeOrder and stops bycriterion for successful completion of handover to EUTRA or cell changeorder is met (the criterion is specified in the target RAT in case ofinter-RAT). At expiry, in case of cell change order from E-UTRA or intraE-UTRA handover, UE may initiate the RRC connection re-establishmentprocedure; In case of handover to E-UTRA, UE may perform the actionsapplicable for the source RAT. Timer T311 starts by initiating the RRCconnection re-establishment procedure and stops by selection of asuitable E-UTRA cell or a cell using another RAT. After expiry UE mayenter RRC_IDLE.

UE may not perform radio link monitoring (RLM) on SCells. eNB mayprevent any UL transmission (PUSCH, SRS and ordered RA) on an SCell by aUE if the UE SCell is in insufficient radio conditions. RLM on SCellsmay not be required. RACH on an SCell in an sTAG may be triggered whensTAG is out-of-sync. RACH on an SCell in an sTAG may also be triggeredwhen sTAG is in-sync. The RACH on an SCell may be used to synchronizesTAG for UL data transmission. In this case, normally PCell is in syncand there may be no need to trigger reestablishment for SCell RACHfailure. The eNB may configure other suitable SCells if available andRRC connection reestablishment may not be needed. In another example,when the eNB detects SCell RACH failure itself, the eNB may deactivateor release the SCell in order to stop preamble transmission or the eNBmay release UL of that SCell or remove the SRS and may stop schedulingon UL resources of that SCell.

RACH triggered on SCell may be unrelated to initial setup, HO, orreestablishment procedure. No further RRC procedure may be used to stopit. UE may autonomously stop SCell RACH process if SCell RACH processfails. When the number of RA preamble transmissions reaches its maximumnumber, the UE may stop preamble transmission. The UE may stop preambletransmission on SCell and may not report Random Access problem to upperlayers when the number of RA preamble transmissions on SCell reachespreambleTransMax. UE may let eNB detect SCell RA failure. eNB may detectRA failure by its own timer. eNB may set the timer value according toconfigured RA parameters (e.g. the maximum number of preambletransmissions, etc). eNB may start a timer when triggering RA on SCellusing a PDCCH order, and upon the timer expiry eNB may consider a RAfailure. When SCell RA fails, eNB may detect the failure without UEreporting it to the eNB. eNB may then take a proper action, such asrestarting RACH process on the same SCell or a different SCell in thesame sTAG, or de-configuring the sCell with failed RACH process. Thisprocess may reduce the number of radio link failures in the system,since there will be no radio link failure in response to random accessprocess failure in sTAGs. Furthermore, automatic detection of randomaccess failure in sTAG by the base station may reduce signalingoverhead, since the UE does not need to inform the base station aboutrandom access failure in an sTAG. In an improved process, random accessprocess failure in the pTAG may initiate radio link failure, but randomaccess process failure in an sTAG does not initiate radio link failure.Furthermore, overhead in signaling is reduced by introducing automaticeNB detection of the random access failure in an sTAG without UEinforming the eNB. This process may increase radio network efficiencyand reduce signaling overhead.

Upon reaching the maximum number of transmitted preambles in an SCell,UE MAC may not indicate RACH failure to RRC. The UE may keep RRCconnection active (UE stays in RRC-connected mode), but stop randomaccess transmission for the initiated random access process (UEconsiders the process unsuccessful). UE does not leave RRC-connectedmode in response to an unsuccessful random access process for an SCell.RRC may not trigger radio link failure (RLF). UE may not report thiscondition to eNB. In a random access process, ifPREAMBLE_TRANSMISSION_COUNTER in the UE is equal to preambleTransMax+1,and the Random Access Preamble is transmitted on the PCell, the UE mayindicate a Random Access problem to upper layers (for example RRClayer). In a random access process, if PREAMBLE_TRANSMISSION_COUNTER inthe UE is equal to preambleTransMax+1, and the Random Access Preamble istransmitted on the SCell, UE may consider the Random Access procedureunsuccessfully completed. At completion of the Random Access procedure,the UE may discard explicitly signalled ra-PreambleIndex andra-PRACH-MaskIndex. At completion of the Random Access procedure, the UEmay stop transmission of the signaled random access preamble in theuplink. UE may stop transmission of random access preamble on an SCellat least until another PDCCH order for transmission of random accesspreamble on the SCell is received from the eNB.

In one example embodiment, eNB may initiate sTAG random access when thesTAG is out-of-sync, when the UE sTAG is in out-of synch state and SCellRA fails, uplink timing is still out-of-sync, and the sTAG may stay inout-of-sync state. When sTAG is in out-of-sync state the following mayoccur: SRS transmissions may be stopped on the corresponding SCells inthe sTAG, the type-0 SRS configuration may be released, the type-1 SRSconfiguration may be maintained, CSI reporting configuration for thecorresponding SCells may be maintained, and/or MAC may flush the uplinkHARQ buffers of the corresponding SCells.

In one example embodiment, eNB may initiate sTAG RA procedure when thesTAG is in-sync. eNB may trigger SCell RA on in-sync SCell, for examplewhen it detects that the uplink timing is deteriorating ortime-alignment timer is expiring, and sTAG needs initial uplinksynchronization. In an example embodiment, if SCell RA fails, eNB and UEmay not change the SCell sync state and TAT for the sTAT may continuerunning until it is expired. eNB may take a proper action upon detectionof RACH failure on sTAG. For example, if there is another SCell in thisTAG, the eNB may trigger RACH in another SCell for sync purpose. TheSCells in sTAG may still be in sync. eNB may start RACH on another cell,which may be completed successfully. UE may not change sTAG status fromin-sync to out-of-sync on its own if RACH-process on an in-sync sTAGfails. sTAG status may change from in-sync to out-of-sync, when TAT ofthe sTAG is expired or is not running.

According to some of the various aspects of embodiments, MAC mayindicate a random access problem to higher layers when random access onPCell fails, and MAC may not indicate a random access problem whenrandom access on SCell fails. No special UE upper layer behavior forSCell UL random access problem may be defined and network-baseddetection and control may be assumed sufficient. Random access failureon SCell may be mainly handled by L1/L2. The eNB may detect randomaccess problem, and there may be less RRC impact compared with PCellRACH failure. PCell Random Access problem may be used by RRC layer totrigger reestablishment procedure. UE may not trigger reestablishmentfor RACH failure on SCell and the eNB may handle RACH failure on SCellitself. UE may not report SCell RACH failure to RRC layer inside UE.

FIG. 13 is an example flow diagram illustrating an unsuccessful randomaccess process as per an aspect of an embodiment of the presentinvention.

According to some of the various embodiments, a wireless device mayrepeatedly transmit a first random access preamble on a primary cell atblock 1300. The transmissions may continue until a condition is met.Example conditions include: until a first random access responsecorresponding to the first random access preamble is received from abase station; or a first predetermined number of transmissions isreached. The first random access preamble may be transmitted one time ifa first random access response is received after the first transmissionof the first random access preamble.

According to some of the various embodiments, at block 1302, if thefirst predetermined number of transmissions is reached without receivingthe first random access response: a random access problem may beindicated to a radio resource control layer in the wireless device; andthe radio resource control layer may determine a radio link failure.

According to some of the various embodiments, at block 1304, thewireless device may receive at least one control message from the basestation. The control message(s) may cause in the wireless device:configuration of a plurality of cells. The plurality of cells maycomprise a primary cell and at least one secondary cell. The controlmessage(s) may cause in the wireless device assignment of each of thesecondary cell(s) to a cell group in a plurality of cell groups. Theplurality of cell groups may comprise a secondary cell group. Thesecondary cell group may comprise a subset of secondary cell(s).

According to some of the various embodiments, the wireless device mayreceive a control command causing the wireless device to transmit asecond random access preamble on a first secondary cell in the secondarycell group. The first secondary cell may be an activated secondary cell.

According to some of the various embodiments, at block 1306, thewireless device may repeatedly transmit the second random accesspreamble until: a second random access response corresponding to thesecond random access preamble is received; or a second predeterminednumber of transmissions is reached.

According to some of the various embodiments, at block 1308, if thesecond predetermined number of transmissions is reached withoutreceiving the second random access response, the wireless device maystop transmission of the second random access preamble; and keep aconnection with the base station active.

According to some of the various embodiments, the first random accessresponse may comprise a first random access preamble identifiercorresponding to the first random access preamble. The second randomaccess response may comprise a second random access preamble identifiercorresponding to the second random access preamble.

According to some of the various embodiments, the wireless device mayenter a no uplink transmission status for the secondary cell group untilat least another control command is received from the base station ifthe second predetermined number of retransmissions is reached.

According to some of the various embodiments, if the secondpredetermined number of transmissions is reached, the wireless devicemay enter an out-of-sync status if the wireless device was in-syncbefore the wireless device receives the control command. If the secondpredetermined number of transmissions is reached, the wireless devicemay stay in the out-of-sync status if the wireless device was in theout-of-sync status before the wireless device receives the controlcommand. The wireless device may stay in an in-sync status if acorresponding time alignment timer of the secondary cell group isrunning when the second predetermined number of transmissions isreached.

According to some of the various embodiments, a connectionre-establishment process may be triggered by the wireless device if thefirst predetermined number of transmissions is reached without receivingthe first random access response.

According to some of the various embodiments, a wireless device mayrepeatedly transmit a first random access preamble on a primary cell atblock 1300 until: a first random access response corresponding to thefirst random access preamble is received from the base station; or afirst predetermined number of transmissions is reached. At block 1302

According to some of the various embodiments, at block 1302, a randomaccess problem to a radio resource control layer in the wireless devicemay be indicated and the radio resource control layer may determine aradio link failure if the first predetermined number of transmissions isreached without receiving the first random access response:

According to some of the various embodiments, at block 1304, thewireless device may receive a control command causing the wirelessdevice to transmit a second random access preamble on a first secondarycell. The control command may comprise a mask index and the randomaccess preamble identifier.

According to some of the various embodiments, at block 1306, thewireless device may repeatedly transmit the second random accesspreamble until: a second random access response corresponding to thesecond random access preamble is received; or a second predeterminednumber of transmissions is reached.

According to some of the various embodiments, at block 1308, thewireless device may stop transmission of the second random accesspreamble and keep a connection with the base station active if thesecond predetermined number of transmissions is reached withoutreceiving the second random access response.

According to some of the various embodiments, a connectionre-establishment process may be triggered by the wireless device if thefirst predetermined number of transmissions is reached without receivingthe first random access response.

According to some of the various embodiments, the primary cell may beassigned to a primary cell group and the first secondary cell may beassigned to a secondary cell group. The uplink signals transmitted bythe wireless device in the primary cell group may employ a firstsynchronization signal transmitted on the primary cell as a first timingreference. The uplink signals transmitted by the wireless device in thesecondary cell group may employ a second synchronization signaltransmitted on an activated secondary cell in the secondary cell groupas a second timing reference. The wireless device may stop uplinktransmissions in the secondary cell group if the second predeterminednumber of transmissions is reached without receiving the second randomaccess response.

According to some of the various embodiments, the wireless device maystop uplink transmissions in the first secondary cell if the secondpredetermined number of transmissions is reached without receiving thesecond random access response.

According to some of the various embodiments, the wireless device mayreceive control message(s) from the base station. The control messagemay comprise the first predetermined number and the second predeterminednumber.

According to some of the various embodiments, the wireless device maycomprise communication interface(s), processor(s), and memory. Thememory may store instructions. The processor(s) may execute theinstructions to cause actions described herein.

According to some of the various embodiments, the wireless device mayrepeatedly transmit a first random access preamble on a primary celluntil: a first random access response corresponding to the first randomaccess preamble is received from the base station; or a firstpredetermined number of transmissions is reached. If the firstpredetermined number of transmissions is reached without receiving thefirst random access response: a random access problem may be indicatedto a radio resource control layer in the wireless device; and the radioresource control layer may determine a radio link failure. The wirelessdevice may receive a control command causing the wireless device totransmit a second random access preamble on a first secondary cell. Thewireless device may repeatedly transmit the second random accesspreamble until: a second random access response corresponding to thesecond random access preamble is received; or a second predeterminednumber of transmissions is reached. If the second predetermined numberof transmissions is reached without receiving the second random accessresponse: transmission of the second random access preamble may bestopped and a connection with the base station may be kept active.

The control command may comprise a mask index and the random accesspreamble identifier. The primary cell may be assigned to a primary cellgroup. The first secondary cell may be assigned to a secondary cellgroup. The first random access response may comprise a first randomaccess preamble identifier corresponding to the first random accesspreamble. The second random access response may comprise a second randomaccess preamble identifier corresponding to the second random accesspreamble.

According to some of the various aspects of embodiments, when the TATassociated with the pTAG expires, all TATs may be considered as expiredand the UE may flush all HARQ buffers of all serving cells, may clearany configured downlink assignment/uplink grants, and/or RRC may releasePUCCH/SRS for all configured serving cells as in Rel-10. The UE may notperform any uplink transmission except the random access preambletransmission when TAT for pTAG is not running.

For primary TAG if timeAlignmentTimer is stopped or expired UE and/oreNB may not indicate the generated positive or negative acknowledgementto the physical layer. If primary TAG timeAlignmentTimer is running, UEand/or eNB may indicate the generated positive or negativeacknowledgement for a TB to the physical layer. The UE may follow LTERel-10 behaviour for DL HARQ feedback handling when the PCell-TAT isstopped or expired.

When the TAT associated with sTAG expires, SRS transmissions may bestopped on the corresponding SCells. In an example implementation, thetype-0 SRS configuration may be released, but the type-1 SRSconfiguration may be maintained. CSI reporting configuration for thecorresponding SCells may be maintained. MAC may flush the uplink HARQbuffers of the corresponding SCells. MAC may stop transmission of HARQfeedback in the downlink to the UE. Whether the SCell-TAT is running ornot may not impact the HARQ feedback transmission in the uplink. UplinkHARQ feedback may be transmitted on PUCCH on PCell, and downlink HARQfeedback may be transmitted on the same or different serving cell asuplink transmission depending on cross carrier scheduling. This processmay improve network performance. Upon expiry of TAT for an sTAG, many ofthe activities in the SCells assigned to sTAG may continue. For example,the UE may still receive downlink data on the SCells, transmit CSI forthe downlink of uplink out-of-sync SCells, and transmit ACK/NACK fordownlink data received on SCells belonging to an out-of-sync sTAG. Thisprocess may not de-configure, deactivate, and/or stop all activities onSCells of out-of-sync sTAG, and therefore may improve overall radio linkefficiency.

FIG. 14 is an example flow diagram illustrating mechanisms in a wirelessdevice when a time alignment timer expires as per an aspect of anembodiment of the present invention. According to some of the variousembodiments, a wireless device may receive control message(s) from abase station at block 1400. The control message(s) may cause in thewireless device configuration of a plurality of cells comprising aprimary cell and at least one secondary cell. The control message(s) maycause in the wireless device assignment of each of the secondary cell(s)to a cell group in a plurality of cell groups. The plurality of cellgroups may comprise a primary cell group and a secondary cell group. Theprimary cell group may comprise a first subset of the plurality ofcells. The first subset may comprise the primary cell. The secondarycell group may comprise a second subset of the secondary cell(s).

According to some of the various embodiments, the control message(s) maycause in the wireless device configuration of a time alignment timer foreach of the plurality of cell groups. The time alignment timer may startor restart in response to the wireless device receiving a timing advancecommand to adjust the uplink transmission timing of a commanded cellgroup in the plurality of cell groups. The commanded cell group may beconsidered out-of-sync in response to the time alignment timer beingexpired or not running. The commanded cell group may be consideredin-sync in response to the time alignment timer running.

The control message(s) may comprise a media access control dedicatedinformation element. The media access control dedicated informationelement may comprise a sequence of first information element(s). Each ofthe first information element(s) may comprise: a first cell group indexof a first secondary cell group; and a first time alignment timer forthe first secondary cell group.

According to some of the various embodiments, when the primary cellgroup becomes out-of-sync, a series of actions may occur as illustratedin example block 1402. For each cell in the primary cell group and thesecondary cell group: the uplink transmission of HARQ feedback may bestopped; re-transmissions of uplink transport blocks in response todownlink HARQ feedback may be stopped; uplink transmissions comprisingtransport block transmissions and channel state informationtransmissions may be stopped; and uplink transmission of at least onerandom access preamble may be allowed if the cell is the primary cell.The random access preamble(s) may be transmitted on the primary cell.

According to some of the various embodiments, a series of actions mayoccur as illustrated in example block 1404 for each activated cell inthe secondary cell group when the secondary cell group becomesout-of-sync and the primary cell group is in-sync. In this case, foreach activated cell in the secondary cell group: re-transmission ofuplink transport blocks in response to downlink negative HARQ feedbackmay be stopped; transmissions of new transport blocks in an uplink ofthe activated cell may be stopped; transmission of HARQ feedback fortransport blocks received on a downlink of the activated cell maycontinue; and transmission of channel state information for the downlinkof the activated cell on an uplink carrier not belonging to thesecondary cell group may be continued. Uplink transmission of at leastone second random access preamble may be allowed on the secondary cellgroup when the secondary cell group becomes out-of-sync and the primarycell group is in-sync.

According to some of the various embodiments, when the secondary cellgroup is out-of-sync and the primary cell group is in-sync, for eachactivated cell in the secondary cell group, the continuing transmissionof HARQ feedback may employ: a physical uplink control channel on theprimary cell; or uplink control information feedback in a transportblock transmitted on a shared data channel of an uplink carrier notbelonging to the secondary cell group. When the secondary cell group isout-of-sync and the primary cell group is in-sync, for each activatedcell in the secondary cell group, the continuing transmission of channelstate information employs: a physical uplink control channel on theprimary cell; or uplink control information feedback in a transportblock transmitted on a shared data channel of an uplink carrier notbelonging to the secondary cell group.

According to some of the various embodiments, for each cell in theplurality of cells, a radio resource control may be notified to releasea sounding reference signal when the primary cell group becomesout-of-sync. For each activated cell in the secondary cell group, aradio resource control may be notified to release a sounding referencesignal when the secondary cell group becomes out-of-sync and the primarycell group is in-sync.

According to some of the various embodiments, the wireless device may beassigned, by the configuration, a plurality of media access controldedicated parameters. The media access control dedicated parameters maycomprise a plurality of time alignment timer values. Each of theplurality of time alignment timer values may be associated with a timealignment timer of a cell group. The wireless device may be assigned, bythe configuration, a plurality of media access control dedicatedparameters comprising a plurality of time alignment timer values, eachof the plurality of time alignment timer values may be associated with aunique cell group in the wireless device.

According to some of the various embodiments, a wireless device mayreceive control message(s) from a base station at block 1400. Thecontrol message(s) may cause in the wireless device configuration of aplurality of cells comprising a primary cell and at least one secondarycell. The control message(s) may cause in the wireless device assignmentof each of the secondary cell(s) to a cell group in a plurality of cellgroups. The plurality of cell groups may comprise a primary cell groupand a secondary cell group. The primary cell group may comprise a firstsubset of the plurality of cells. The first subset may comprise theprimary cell. The secondary cell group may comprise a second subset ofthe secondary cell(s). The control message(s) may cause in the wirelessdevice configuration of a time alignment timer for each of the pluralityof cell groups. The time alignment timer may start or restart inresponse to the wireless device receiving a timing advance command toadjust uplink transmission timing of a commanded cell group in theplurality of cell groups.

According to some of the various embodiments, the wireless device mayreceive timing advance command(s) from the base station. The timingadvance command may comprise: a time adjustment value; and an indexidentifying the secondary cell group. The timing advance command(s) maybe configured to cause substantial alignment of reception timing of theuplink signals in frames and subframes of the secondary cell group atthe base station. The time alignment timer of the secondary cell groupmay be restarted in response to receiving a timing advance command inthe at least one timing advance command.

According to some of the various embodiments, as illustrated in block1402, when a first time alignment timer of the primary cell groupexpires, for each cell in the primary cell group and the secondary cellgroup: uplink transmission of HARQ feedback may be stopped;re-transmissions of uplink transport blocks in response to downlink HARQfeedback may be stopped; uplink transmissions comprising transport blocktransmissions and channel state information transmissions may bestopped; and uplink transmission of at least one random access preamblemay be allowed if the cell is the primary cell.

The primary cell group may comprise a first subset of the plurality ofcells. The first subset may comprise the primary cell. Uplinktransmissions by the wireless device in the primary cell group mayemploy a first synchronization signal transmitted on the primary cell.The second cell group may comprise a second subset of the plurality ofcells. The second subset may comprise a reference secondary cell. Uplinktransmissions in the secondary cell group may employ a secondsynchronization signal on the reference secondary cell as a secondarytiming reference.

According to some of the various embodiments, as illustrated in block1404, when a second time alignment timer of the secondary cell groupexpires and the first time alignment timer is running, for eachactivated cell in the secondary cell group: re-transmission of uplinktransport blocks in response to downlink negative HARQ feedback may bestopped; transmissions of new transport blocks in an uplink of theactivated cell may be stopped; transmission of HARQ feedback fortransport blocks received on a downlink of the activated cell may becontinued; and transmission of channel state information for thedownlink of the activated cell on an uplink carrier not belonging to thesecondary cell group may be continued.

According to some of the various embodiments, the wireless device maycomprise communication interface(s), processor(s), and memory. Thememory may store instructions. The processor(s) may execute theinstructions to cause actions described herein.

According to some of the various embodiments, the wireless device mayreceive at least one control message from a base station at 1400. Thecontrol message(s) may cause in the wireless device configuration of aplurality of cells. The plurality of cells may comprise a primary cellsecondary cell(s). The control message(s) may cause in the wirelessdevice assignment of each of the secondary cell(s) to a cell group in aplurality of cell groups. The plurality of cell groups may comprise aprimary cell group and a secondary cell group. The primary cell groupmay comprise a first subset of the plurality of cells. The first subsetmay comprise the primary cell. The secondary cell group may comprise asecond subset of the secondary cell(s). The control message(s) may causein the wireless device configuration of a time alignment timer for eachof the plurality of cell groups. The time alignment timer may start orrestart in response to the wireless device receiving a timing advancecommand to adjust uplink transmission timing of a commanded cell groupin the plurality of cell groups.

The control message(s) may comprise a media access control dedicatedinformation element. The media access control dedicated informationelement may comprise a sequence of first information element(s). Each ofthe first information element(s) may comprise: a first cell group indexof a first secondary cell group; and a first time alignment timer forthe first secondary cell group.

According to some of the various embodiments, at block 1402, when afirst time alignment timer of the primary cell group expires, for eachcell in the primary cell group and the secondary cell group: uplinktransmission of HARQ feedback may be stopped; re-transmissions of uplinktransport blocks in response to downlink HARQ feedback may be stopped;uplink transmissions comprising transport block transmissions andchannel state information transmissions may be stopped; and uplinktransmission of random access preamble(s) may be allowed if the cell isthe primary cell. The random access preamble(s) may be transmitted onthe primary cell.

According to some of the various embodiments, at block 1402, when asecond time alignment timer of the secondary cell group expires and thefirst time alignment timer is running, for each activated cell in thesecondary cell group: re-transmission of uplink transport blocks inresponse to downlink negative HARQ feedback may be stopped;transmissions of new transport blocks in an uplink of the activated cellmay be stopped; transmission of HARQ feedback for transport blocksreceived on a downlink of the activated cell may be continued; andtransmission of channel state information for the downlink of theactivated cell on an uplink carrier not belonging to the secondary cellgroup may be continued.

The wireless device may be assigned, by the configuration, a pluralityof media access control dedicated parameters. The media access controldedicated parameters may comprise a plurality of time alignment timervalues. Each of the time alignment timer values may be associated with atime alignment timer of a cell group. The wireless device may beassigned, by the configuration, a plurality of media access controldedicated parameters. The media access control dedicated parameters maycomprise a plurality of time alignment timer values. Each of the timealignment timer values may be associated with a unique cell group in thewireless device.

The wireless device may transmit a second random access preamble on asecondary cell of the secondary cell group in response to receiving acontrol command from the base station when: the second time alignmenttimer of the secondary cell group is expired; and the first timealignment timer is running.

Frames and subframe transmission timing for all downlink carriers in theprimary cell group and the secondary cell group of a base station may besubstantially time aligned with each other. Frames and subframe for alldownlink carriers in the primary cell group and the secondary cell groupare transmitted and their timing are controlled by the same basestation, and therefore achieving an accurate time alignment by the basestation would be feasible by the base station. The accuracy would bebetter than a fraction of a subframe, for example 10 micro-sec orbetter. For example, timing alignment error between downlink carriersbelonging to different bands may be within 1.3 micro-seconds. In anotherexample, for carriers in the same band the synchronization may be moreaccurate and may be below 1 micro-second.

According to some of the various aspects of embodiments, frames andsubframe transmission timing for all downlink carriers in the primarycell group and the secondary cell group of the base station may besubstantially time aligned with frames and subframe transmission timingof all downlink carriers in the plurality of base stations. This may bean optional synchronization requirement to enhance network performanceand some network may not use this requirement. Such a time alignmentrequires, for example, coordination and signalling among the pluralityof base stations. In another example, it requires that the plurality ofbase stations use the same synchronization source such as GPSsignalling, some other sort of centralized algorithm, and/or some packetbased synchronization system to achieve synchronization. Time alignmentprocess between frames and subframes of the plurality of base stationsthus may involve many external factors, and therefore the accuracy oftime alignment may not be precise, but it may be substantially withincertain pre-defined accuracy limits. Time alignment between carriers ofthe same base stations may be a simpler task compared with timealignment between carriers of multiple base stations. The accuracy ofthe former task may be higher than the accuracy of the later task.Therefore, the term substantially aligned here may imply that thecarriers are substantially time aligned within a certain time alignmentaccuracy range. For example, in an implementation the error may be belowhalf a subframe, a small fraction of a subframe, or for example 10micro-seconds, or less.

Frames and subframe transmission timing for all uplink carriers in theprimary cell group of the wireless device may be substantially timealigned with each other. Frames and subframe transmission timing for alluplink carriers in the secondary cell group of the wireless device maybe substantially time aligned with each other. Frames and subframetransmission timing for uplink carriers in the primary cell group of thewireless device may not necessarily be time aligned with frames andsubframe transmission timing for uplink carriers in the secondary cellgroup of the wireless device. Uplink transmission timing in differentcell groups in the wireless device may be adjusted according to adifferent set of MAC time alignment commands, and may employ a differentCell timing reference. Substantial time alignment here may be consideredin the context. In a wireless device, uplink signal transmission may nottime aligned if they are not precisely time aligned. A wireless devicemay use a different downlink synchronization signals and/or timealignment commands to align uplink transmission in different carriergroups. Because the same device is generating the signal. Thesubstantial alignment here may imply that the wireless device makesevery effort to align transmission timing and may use the same timingreference. However, uplink transmission timing of uplink carriers in theprimary cell group and the secondary cell group may not be exactly timealigned. Different cell groups use different downlink synchronizationsignals as the reference timing, and time alignment commands for theuplink are different for the primary cell group and secondary cell groupuplink transmission. In an example, in a wireless signal uplinktransmission even a few micro-second mis-alignment between uplinktransmissions in two different carrier groups may be considered as notbeing substantially time aligned. Uplink transmission timing betweencells in different cell groups, for example may differ up to 30micro-seconds depending on cell radius, repeater locations, and/or thelike.

According to a first embodiment, the plurality of time alignmentcommands may substantially align frame and subframe reception timing ofsignals transmitted by the plurality of wireless devices to the basestation in the primary cell group. The plurality of time alignmentcommands may substantially align frame and subframe reception timing ofsignals transmitted by the plurality of wireless devices to the basestation in the secondary cell group. The base station may employ timealignment commands in order to substantially time align uplink signalsreceived from the same carrier group in different wireless devices, eventhough signal propagation/processing time may be different for differentcarrier groups. Each device may have a different signalpropagation/processing delay, because of its distance to the basestation, or its receiver structure, and/or the like. In this context,the substantial time alignment criteria is determined by a base stationperformance criteria, and in normal condition the base station maytransmit the time alignment commands with the goal of achieving asubstantial time alignment in the uplink. When signal reception timingin the base station deviates more than a threshold from a reference timefor signals received from a wireless device, the base station maytransmit a time alignment command to adjust the wireless devicetransmission timing. The reference eNB reception time may not be exactlythe same for different carrier groups. The TA commands may have aresolution in the range of 1.6 micro-seconds.

According to a second embodiment, the plurality of time alignmentcommands may substantially align frame and subframe reception timing ofsignals transmitted by the plurality of wireless devices to the basestation in the primary cell group and the secondary cell group. In thisembodiment, time alignment commands are transmitted in order to maintainthe same reception timing at the base station among all carriers of thecell, including all carriers in the primary cell group and secondarycell group. This process may require a more complex time alignmentprocedure in the base station, but may provide advantages because framesand subframes of all uplink transmissions by all wireless devices on alluplink carriers are substantially the same in the base station. Thesubstantial time alignment implies that the base station may transmittime alignment commands to achieve such a time alignment in the receivedsignal of all uplink carriers from all wireless devices in the coveragearea of for example a base station sector. The base station may employtime alignment commands in order to substantially time align uplinksignals received from different carrier groups in the same wirelessdevice as well as signals received from a plurality of wireless devices,even though signal propagation/processing time may be different fordifferent carrier groups and from different wireless devices. Whensignal reception timing in the base station deviates more than athreshold from a reference time for signals received from a wirelessdevice, the base station may transmit a time alignment command to adjustthe wireless device transmission timing. The reference eNB receptiontime may be the same for different wireless devices and for differentcarrier groups. The TA commands may have a resolution in the range of1.6 micro-seconds.

FIG. 15 is an example flow diagram illustrating a base station processfor configuring multiple cell groups as per an aspect of an embodimentof the present invention. According to some of the various embodiments,a base station in a plurality of base stations may transmit controlmessage(s) to a wireless device at block 1500. The plurality of basestations may be compatible with LTE release 11 or above and supportmultiple timing advance groups.

According to some of the various embodiments, the control message(s) maybe configured to cause in the wireless device configuration of aplurality of cells. The plurality of cells may comprise a primary celland at least one secondary cell. The control message(s) may beconfigured to cause in the wireless device to assign of each of thesecondary cell(s) to a cell group in a plurality of cell groups. Theplurality of cell groups may comprise a primary cell group and asecondary cell group. The primary cell group may comprise a first subsetof the plurality of cells. The first subset may comprise the primarycell. Uplink transmissions by the wireless device in the primary cellgroup may employ a first synchronization signal transmitted on theprimary cell as a primary timing reference. The secondary cell group maycomprise a second subset of the secondary cell(s). The second subset maycomprise a reference secondary cell. Uplink transmissions in thesecondary cell group may employ a second synchronization signal on thereference secondary cell as a secondary timing reference.

According to some of the various embodiments, control message(s) may beconfigured to modify a radio bearer. Control message(s) may beconfigured to cause in the wireless device configuration of uplinkrandom access resources on the reference secondary cell.

According to some of the various embodiments, a plurality of timingadvance commands may be transmitted by the base station to the wirelessdevice at block 1502. Each of the plurality of timing advance commandsmay comprise a time adjustment value and an index identifying a cellgroup.

According to some of the various embodiments, frames and subframestransmission timing for downlink carriers in the primary cell group anddownlink carriers in the secondary cell group may be substantially timealigned with each other. Frames and subframes transmission timing fordownlink carriers in the primary cell group and downlink carriers in thesecondary cell group of the base station may be substantially timealigned with frames and subframes transmission timing of downlinkcarriers of other base stations in the plurality of base stations.Frames and subframes transmission timing for uplink carriers in theprimary cell group of the wireless device may be substantially timealigned with each other. Frames and subframes transmission timing foruplink carriers in the secondary cell group of the wireless device maybe substantially time aligned with each other. Frames and subframestransmission timing for uplink carriers in the primary cell group and inthe secondary cell group of the wireless device may employ: differentsynchronization signals as a timing reference; and different timingadvance commands. The plurality of timing advance commands may beconfigured to cause the wireless device to adjust timing of uplinksignal transmissions in uplink carriers of the primary cell group andthe secondary cell group such that the base station receives the uplinksignal transmissions in substantial alignment with frames and subframesof the base station. Transmission time may be divided into frames. Eachframe may be divided into a plurality of subframes.

According to some of the various embodiments, frames and subframereception timing for uplink carriers in the primary cell group anduplink carriers in the secondary cell group of the base station may besubstantially time aligned with frames and subframe reception timing ofuplink carriers of other base stations in the plurality of basestations. Frames and subframes transmission timing for uplink carriersin the primary cell group and in the secondary cell group of thewireless device may not necessarily time aligned.

According to some of the various embodiments, the wireless device may beassigned, by the configuration, a plurality of media access controldedicated parameters. The media access control dedicated parameters maycomprise a plurality of time alignment timer values. Each of theplurality of time alignment timer values may be associated with a uniquecell group in the wireless device.

According to some of the various embodiments, the base station maytransmit a control command configured to cause transmission of a randomaccess preamble on random access resources of the reference secondarycell in the secondary cell group. The base station may transmit a randomaccess response on a primary cell in the primary cell group. The randomaccess response may comprise a timing advance command for the secondarycell group. The secondary cell group may comprise the referencesecondary cell. The control command may comprise a mask index and therandom access preamble identifier. The random access response maycomprise an identifier of the random access preamble.

According to some of the various embodiments, a base station in aplurality of base stations may transmit first control message(s) to awireless device at block 1500. The plurality of base stations may becompatible with LTE release 11 or above.

According to some of the various embodiments, the first controlmessage(s) may be configured to cause in the wireless deviceconfiguration of a plurality of cells. The plurality of cells maycomprise a primary cell and at least one secondary cell. The firstcontrol message(s) may be configured to cause in the wireless deviceassignment of each of the secondary cell(s) to a cell group in aplurality of cell groups. The plurality of cell groups may comprise aprimary cell group and a secondary cell group. The primary cell groupmay comprise a first subset of the plurality of cells. The first subsetmay comprise the primary cell. The secondary cell group may comprise asecond subset of the secondary cell(s).

According to some of the various embodiments, the base station maytransmit a plurality of timing advance commands to the wireless deviceat block 1502. Each of the plurality of timing advance commands maycomprise a time adjustment value and an index identifying a cell group.

According to some of the various embodiments, frames and subframestransmission timing for downlink carriers in the primary cell group anddownlink carriers in the secondary cell group may be substantially timealigned with each other. Frames and subframes transmission timing fordownlink carriers in the primary cell group and downlink carriers in thesecondary cell group of the base station may be substantially timealigned with frames and subframes transmission timing of downlinkcarriers of other base stations in the plurality of base stations.Frames and subframes transmission timing for uplink carriers in theprimary cell group of the wireless device may be substantially timealigned with each other. Frames and subframes transmission timing foruplink carriers in the secondary cell group of the wireless device maybe substantially time aligned with each other. Frames and subframestransmission timing for uplink carriers in the primary cell group and inthe secondary cell group of the wireless device may employ differentsynchronization signals as a timing reference and different timingadvance commands. The plurality of timing advance commands may beconfigured to cause the wireless device to adjust timing of uplinksignal transmissions in uplink carriers of the primary cell group andthe secondary cell group such that the base station receives the uplinksignal transmissions in substantial alignment with frames and subframesof the base station.

The base station may transmit a control command configured to causetransmission of a random access preamble on random access resources ofthe reference secondary cell in the secondary cell group. The basestation may transmit a random access response on a primary cell in theprimary cell group. The random access response may comprise a timingadvance command for the secondary cell group. The secondary cell groupmay comprise the reference secondary cell. The control command maycomprise a mask index and the random access preamble identifier. Therandom access response may comprise an identifier of the random accesspreamble.

According to some of the various embodiments, the base station maycomprise communication interface(s), processor(s), and memory. Thememory may store instructions. The processor(s) may execute theinstructions to cause actions described herein.

FIG. 7 is an example message flow in a random access process in a TAG asper an aspect of an embodiment of the present invention. A preamble 602may be sent by a UE in response to the PDCCH order 601 on an SCellbelonging to an sTAG. Preamble transmission for SCells may be controlledby the network using PDCCH format 1A. Msg2 message 603 in response tothe preamble transmission on SCell may be addressed to RA-CRNTI in PCellcommon search space (CSS). Uplink packets 604 may be transmitted on athe SCell, in which the preamble was transmitted.

In an implementation, the SCell index in the uplink grant may not betransmitted in the uplink grant in RAR and the uplink grant contained inthe RAR may be applicable to the cell where the preamble was sent.According to some of the various aspects of embodiments RAPID may beincluded in Msg2 to address possible preamble misdetection by the eNB.UE may compare the RAPID in Msg2 with the transmitted preamble ID toverify the validity of the Msg2 and to verify possible preamblemisdetection by eNB.

If a UE receives an RRC message that causes the UE to be configured totransmit SRS signal on an SCell, the UE may transmit SRS signal afterthe SCell is active and in-sync. If the sTAG and the activated SCell arein-sync then UE may start transmission of one or more SRS signals afterthe SCell is being activated. In an example embodiment, if an SCell isconfigured with transmission of SRS signals and is associated with ansTAG that is out-of-sync. eNB may activate the SCell and eNB mayinitiate RA process on an SCell in the sTAG. UE may not transmit any SRSsignals on the SCell before successful completion of random accessprocess. In response to successful completion of RA process in the sTAGand applying the timing advance command, the UE may start transmissionof one or more SRS signals on uplink of the SCells (in the sTAG) withconfigured SRS transmission. UE may not transmit any SRS signal in theuplink of an active SCell belonging to an out-of-sync sTAG. When SRS isconfigured for an SCell belonging to an out-of-sync sTAG, a UE may notsend SRS until UE receives and applies a RAR including a TA value, andan UL grant, because otherwise SRS may be sent with incorrecttransmission power and/or timing. UE may apply TA value to the sTAG. Inan example embodiment, UE may apply the power control command in theuplink grant before starting transmission of one or more SRS signals. Inan example embodiment Uplink grant may include power controlinformation. The UE may receive TA value, uplink resources and a powercontrol command (TPC) to adjust the uplink transmission timing and powerbefore the UE starts to send SRS (if configured for the SCell).Transmission of one or more SRS signal may start after the SCell isactivated and in-sync. This process may not be required for SCells ofthe pTAG, because pTAG may be in-sync when an SCell is activated.

For an active and in-sync SCell, one or more SRS signals transmissionmay be dropped in a subframe if UE has insufficient power to transmitSRS signal with other uplink data or control packets in the subframe.SRS signal may also be dropped if it collides with other uplinktransmissions. For example, a UE may not simultaneously transmit uplinkdata and SRS in a subframe of an SCell. Transmission of one or more SRSsignal may start after the SCell is activated and in-sync. Then for eachsubframe that SRS is configured to be transmitted, UE may examine powerand other parallel transmission constraints and may drop or transmit anSRS signal in a subframe of an SCell if all other conditions are met.Therefore the UE may transmit one or more SRS signals after the SCell isactivated and is in-sync. The UE may also drop one or more SRS signalsdepending on other predefined conditions after the SCell is activatedand is in-sync. But prior to applying TAT to an activated andout-of-sync SCell no SRS signal may be transmitted on the SCell. Thisprocess may increase the transmission time and/or power of thetransmitted SRS signals. Otherwise, SRS signal transmission may overlapwith other symbols, and deteriorate radio link performance.

FIG. 16 is an example flow diagram illustrating a process for soundingtransmission as per an aspect of an embodiment of the present invention.

According to some of the various embodiments, a wireless device mayreceive at least one control message from a base station at block 1600.The control message(s) may cause in the wireless device configuration ofa plurality of cells. The plurality of cells may comprise a primary celland at least one secondary cell. The control message(s) may cause in thewireless device an assignment of each of the secondary cell(s) to a cellgroup in a plurality of cell groups. The plurality of cell groups maycomprise a primary cell group and a secondary cell group. The primarycell group may comprise a first subset of the plurality of cells. Thefirst subset may comprise the primary cell. Uplink transmissions by thewireless device in the primary cell group may employ a firstsynchronization signal transmitted on the primary cell as a primarytiming reference. The secondary cell group may comprise a second subsetof the secondary cell(s). Control message(s) may cause in the wirelessdevice configuration of transmissions of sounding reference signals on asecondary cell in the secondary cell group. Control message(s) may causeconfiguration of the random access resources.

According to some of the various embodiments, the wireless device mayreceive an activation command to activate the secondary cell in thewireless device at block 1602.

According to some of the various embodiments, at block 1604, thewireless device may receive a control command configured to causetransmission of a random access preamble on random access resources ofone of the secondary cell(s) in the second subset.

According to some of the various embodiments, at block 1606, thewireless device may receive a random access response. The random accessresponse may comprise a timing advance command for the secondary cellgroup. The random access response may comprise a preamble identifier.The preamble identifier may identify the random access preamble.

According to some of the various embodiments, at block 1608, thewireless device may transmit one or more of the sounding referencesignals on the secondary cell after applying the timing advance commandto the secondary cell group. The wireless device may be configured tonot transmit any of the sounding reference signals on the secondary cellduring the period: between receiving the activation command and applyingthe timing advance command; or when the secondary cell is inactive; orwhen a time alignment timer for said secondary cell group is notrunning. Applying the timing advance command may cause substantialalignment of reception timing of uplink signals in frames and subframesof the secondary cell group at the base station.

According to some of the various embodiments, the wireless device may beconfigured to transmit at least one of the sounding reference signalsif: the secondary cell is activated; the timing advance command isapplied by the wireless device to the secondary cell group; and a timealignment timer for the secondary cell group is running. Even when theseconditions are met, the sounding reference signals may be dropped due toinsufficient wireless device transmit power or due to coinciding withother transmissions in the same cell group.

The sounding reference signal(s) may be type zero sounding referencesignals. The sounding reference signal(s) may be configured to betransmitted during a period. The sounding reference signal(s) may betransmitted on the last symbol of a plurality of subframes.

The transmission of a sounding reference signal in the soundingreference signal(s) in a subframe of the secondary cell may be droppedif the wireless device is power limited in the subframe. Thetransmission of a sounding reference signal in the sounding referencesignal(s) in a subframe of the secondary cell may be dropped if thewireless device transmits data in the subframe of the secondary cell.The wireless device may drop at least one sounding reference signal ifone or more pre-defined conditions are met.

According to some of the various embodiments, a wireless device mayreceive at least one control message from a base station at block 1600.The control message(s) may cause in the wireless device configuration ofa plurality of cells. The plurality of cells may comprise a primary celland at least one secondary cell. The control message(s) may cause in thewireless device an assignment of each of the secondary cell(s) to a cellgroup in a plurality of cell groups. The plurality of cell groups maycomprise a primary cell group and a secondary cell group. The primarycell group may comprise a first subset of the plurality of cells. Thefirst subset may comprise the primary cell. Uplink transmissions by thewireless device in the primary cell group may employ a firstsynchronization signal transmitted on the primary cell as a primarytiming reference. The secondary cell group may comprise a second subsetof the secondary cell(s).

According to some of the various embodiments, the wireless device mayreceive an activation command to activate the secondary cell in thewireless device at block 1602.

According to some of the various embodiments, at block 1604, thewireless device may receive a control command configured to causetransmission of a random access preamble on random access resources ofone of the secondary cell(s) in the second subset.

According to some of the various embodiments, at block 1606, thewireless device may receive a random access response. The random accessresponse may comprise a timing advance command for the secondary cellgroup. The random access response may comprise a preamble identifier.The preamble identifier may identify the random access preamble.

According to some of the various embodiments, the wireless device mayreceive a second control message from the base station. The secondcontrol message may cause, in the wireless device, configuration oftransmissions of sounding reference signals on a secondary cell in thesecondary cell group.

According to some of the various embodiments, at block 1608, thewireless device may transmit one or more of the sounding referencesignals on the secondary cell after applying the timing advance commandto the secondary cell group. The wireless device may be configured tonot transmit any of the sounding reference signals on the secondary cellduring the period: between receiving the activation command and applyingthe timing advance command; or when the secondary cell is inactive; orwhen a time alignment timer for said secondary cell group is notrunning. Applying the timing advance command may cause substantialalignment of reception timing of uplink signals in frames and subframesof the secondary cell group at the base station.

According to some of the various embodiments, the wireless device may beconfigured to transmit at least one of the sounding reference signalsif: the secondary cell is activated; the timing advance command isapplied by the wireless device to the secondary cell group; and a timealignment timer for the secondary cell group is running. Even when theseconditions are met, the sounding reference signals may be dropped due toinsufficient wireless device transmit power or due to coinciding withother transmissions in the same cell group.

The control message(s) may be configured to further cause in thewireless device the configuration of a time alignment timer for each ofthe plurality of cell groups. The time alignment timer may start orrestart in response to the wireless device receiving a timing advancecommand to adjust uplink transmission timing of a commanded cell groupin the plurality of cell groups.

According to some of the various embodiments, the wireless device maycomprise communication interface(s), processor(s), and memory. Thememory may store instructions. The processor(s) may execute theinstructions to cause actions described herein.

LTE Rel-8, 9 & 10 Timing Advance Command MAC command has a subheader anda MAC CE with fixed size of one octet that contains 2 reserved bits (Rbits). LTE Rel-8, 9 & 10 does not support multiple time alignmentgrouping (It may also be said: it supports only one time alignmentgroup) and there is no need to indicate to which time alignment groupthe time alignment command may apply. The time alignment command isapplied to uplink carriers including PCell and SCell(s) of a wirelessdevice. There is a need for enhancing the time alignment procedure inLTE Rel-8, 9 & 10 to efficiently support multiple time alignment groups.

In release 11 or above, when multiple TAGs are configured, a MAC CEidentifying the TA group to which the TA value applies may be used. TheR bits may be used to signal the TA group to which the TA value applies.The R bits of the Timing Advance Command MAC Control Elements may beused to signal the TA Group. In this embodiment, one TA is included in aMAC CE. If multiple TAs, each for a different TAG, need to betransmitted, then multiple CEs may be transmitted in the same TTI ordifferent TTIs. When multiple time alignment CEs are transmitted to awireless device in a TTI, a CE may have its own MAC subheader, and LCIDnumber may be the same for them. It may be possible to transmit multipleTA MAC CE to a given wireless device in the same TTI, and a TA MAC CEmay have its own subheader.

According to some of the various aspects of embodiments, when the R bitsare set to 0, MAC CE indicates the TA Group of the PCell (pTAG) andother values are addressed to other TA groups (sTAGs). This would allowfor a maximum of 4 TA Groups. 0 may be used for the 2-bits correspond topTAG (00), 1-3 (01, 10, 11) may be used for sTAGs. This solutionminimizes the changes to the release 8, 9, 10 MAC layer, and enhancesthe MAC CE TA command to multiple TAGs.

RRC layer may configure TAGs for an SCell (implicitly or explicitly) andmay assign a TAG index (or TAG identifier) to a TAG (implicitly orexplicitly). The index that is introduced for a TA Group in RRC may beused for the setting of the TAG-ID bits. The RRC index of the TA Groupsis used for the setting of the TAG-ID bits. TAG-ID configured by RRC maybe used to indicate TA group where the TA command applies. This mayimply that the RRC signalling may configure up to 4 TAG-IDs.

One TAG in one TA Command may be supported. R.11 or above UEs may checkR bits in MAC CE, but R.10 or below UEs may not need to check the Rbits. According to some of the various aspects of embodiments, an R.11or above UE with one configured TAG (only pTAG) may not need to checkthe TAG-ID bits. According to some of the various aspects ofembodiments, multiple TAG TA values may be supported in one MAC CE TAcommand, in which a TA applies to a TAG. A 6-bit TA value may beassociated with a TAG using 2-bit TAG index (identifier).

This enhancement supports transmitting TA value for a specific TAGwithout adding the size of MAC CE command compared to release 8, 9, 10.Two bits of TAG index bits are introduced before the 6 bits of TA value.This may require a new definition for MAC CE command that would beapplicable to release 11 or above UEs. A method to introduce this newMAC CE command is to introduce a new MAC LCID for this new format. MACLCID is included in a MAC subheader. This is a viable implementationoption. This may increase the number of used MAC LCIDs. An embodiment isintroduced here that would allow to use the same MAC LCID as in Rel-8, 9& 10 for Rel-11 multiple TAG configuration. The same LCID as in Rel-8, 9& 10 may be used in this embodiment applicable to multiple TAGconfiguration in release 11 or beyond. eNB transmits TA MAC CEs to UEsin unicast messages. eNB has the information about the current LTErelease supported by the UE. This information may be available to theeNB via network signaling (through S1 interface with the MME) or via airinterface signaling (UE capability message received from the UE). eNBmay use the same LCID for the legacy TA MAC CE and the newly introducedTA MAC CE. If the MAC CE is transmitted to the release 8, 9, 10 LTE UEs,then the R bits may not include a TAG index. If the MAC CE istransmitted to the release 11 or above UEs, then the R bits may includethe TAG index if multiple TAGs are configured. If multiple TAGs are notconfigured, then TA value is applied to pTAG including all the carriers.

This enhancement may not require introducing a new LCID, although a newMAC CE format is introduced for transmitting TA commands. Both legacy TAMAC CEs and new TA MAC CEs may use the same LCID and that reduces thenumber of LCIDs used in the MAC layer (compared with the scenario wherea new LCID is introduced) and may further simplify UE implementation.eNB may consider UE LTE release or may consider the number of configuredTAGs (1 for pTAG only configuration, more than 1 for pTAG and sTAGconfiguration) to decide if legacy MAC CE format should be used or newMAC CE format should be used. If UE is a release 8, 9, 10, then legacyMAC CE is used. For release 11 or above UEs with one TAG configuration(only pTAG), eNB may use new MAC CEs with TAG-ID bits set to pTAG index(for example 0 for pTAG). For release 11 or above UEs (or for release 11or above UEs with multiple TAG configuration), eNB may use the new MACCE format, wherein 2-bit TAG-ID bits point to the TAG index, which wasconfigured in UE using RRC configuration messages.

In an example, user terminals (for example: UE1, UE2) communicating withan eNB may support different releases of LTE technology. For example,UE2 may support releases 8, 9, 10, and 11 of LTE, and UE1 may supportreleases 8, 9 and/or 10 (or for example may support release 8, or maysupport 8 & 9). In another example, user terminals (for example: UE1,UE2) communicating with an eNB may support different capabilities of LTEtechnology. For example, UE2 may support multiple time alignment groups,and UE1 may not support multiple time alignment groups. eNB may send MACTA CEs to the user terminals (UE1, UE2) in unicast messages. MAC TA CEsmay have the same LCID for UE1 and UE2. The user terminals (UE1, UE2)may interpret MAC TA CE messages for adjusting uplink timing differentlydependent on the LTE release they support and are operating. The sameexact message may be processed differently by UE1 and UE2. For example,in a scenario, where MAC LCID indicate MAC TA CE, and RR field is 00,UE1 may not consider the value of the two bits before TA value (RR). UE1may change the uplink transmission timing for all uplink carriersaccording to the TA value in the MAC command. UE2 may however, decodethe value of two bits before TA value (RR=TAG ID), and when the two bitsare for example 00, UE1 may only update the transmission timing forcells belonging to pTAG according to the TA value. The first two bitsmay indicate the TAG ID to which the TA may apply. Therefore, the sameMAC CE message content may be processed differently by different UEsoperating in different LTE releases.

According to some of the various aspects of embodiments, a base stationmay transmit a plurality of unicast timing advance commands to aplurality of wireless devices for adjusting uplink transmission timingby the plurality of wireless devices. Each of the plurality of wirelessdevices may operate in a mode. The mode may comprise: a) a first modeemployable by all of the plurality of wireless devices, or a second modeemployable only by a subset of the plurality of wireless devices. Eachof the plurality of wireless devices being addressed by at least one ofthe plurality of unicast timing advance commands may interpretdifferently the at least one of the plurality of unicast timing advancecommands depending on the mode in which each of the plurality ofwireless devices is operating. The plurality of unicast timing advancecommands may have different formats for the plurality of wirelessdevices operating in the first mode and the plurality of wirelessdevices operating in the second mode. The format may comprise: a) asubheader comprising a logical channel ID, the logical channel ID beingthe same for the plurality of unicast timing advance commands, and b) acontrol element comprising a timing advance value, c) 2-bit informationinterpreted differently depending on the wireless device mode. The firstmode may be configured to be compatible with release 8, 9 or 10 ofLTE-Advance technology. The second mode may be configured to becompatible with release 11 of LTE-Advance technology.

FIG. 15 is an example flow diagram illustrating a base station processfor configuring multiple cell groups as per an aspect of an embodimentof the present invention. According to some of the various embodiments,a base station in a plurality of base stations may transmit controlmessage(s) to a first wireless device at block 1500. The plurality ofbase stations may be compatible with LTE release 11 or above and supportmultiple timing advance groups.

According to some of the various embodiments, the control message(s) maybe configured to cause in the first wireless device configuration of aplurality of cells. The plurality of cells may comprise a primary celland at least one secondary cell. The control message(s) may beconfigured to cause in the first wireless device to assign of each ofthe secondary cell(s) to a cell group in a plurality of cell groups. Theplurality of cell groups may comprise a primary cell group and asecondary cell group. The primary cell group may comprise a first subsetof the plurality of cells. The first subset may comprise the primarycell. The secondary cell group may comprise a second subset of thesecondary cell(s). The second subset may comprise a reference secondarycell.

According to some of the various embodiments, the control message(s) maybe configured to modify a radio bearer. Control message(s) may betransmitted by the base station to the first wireless device. Thecontrol message may cause configuration of uplink random accessresources on a secondary cell in the secondary cell group. Controlmessage(s) may comprise a plurality of random access resourceparameters. The plurality of random access resource parameters maycomprise: an index; a frequency offset; and a plurality of sequenceparameters. Control message(s) may comprise a time alignment timerparameter for each cell group in the plurality of cell groups.

According to some of the various embodiments, a plurality of timingadvance commands may be transmitted by the base station to the firstwireless device at block 1502. A second plurality of timing advancecommands may be transmitted by the base station to a second wirelessdevice. The second wireless device may be unconfigurable with cellgroups.

According to some of the various embodiments, each command in the firstplurality of timing advance commands and the second plurality of timingadvance commands may consist of a MAC subheader and a MAC controlelement. All of the MAC subheaders may comprise the same logical channelidentifier value. Each of the first plurality of timing advance commandsmay comprise two bits. The content of the two bits may indicate a firstcell group index. The first cell group index may identify a first cellgroup according to the configuration caused by the control message(s).Each of the first plurality of timing advance commands may be configuredto cause substantial alignment of reception timing of first uplinksignals in frames and subframes at the base station. The first uplinksignals may be transmitted by the first wireless device in one or moreactivated uplink carriers of a cell group identified by the two bits.Each of the second plurality of timing advance commands may comprise tworeserved bits. Each of the second plurality of timing advance commandsmay be configured to cause substantial alignment of reception timing ofsecond uplink signals in frames and subframes at the base station. Thesecond uplink signals may be transmitted by the second wireless devicein one or more activated uplink carriers.

According to some of the various embodiments, the timing advance commandin the first plurality of timing advance commands may comprise a timingadvance value and an index identifying the secondary cell group. Thetiming advance command may be configured to cause substantial alignmentof reception timing of third uplink signals in frames and subframes ofthe secondary cell group at the base station.

According to some of the various embodiments, the wireless device may beassigned, by the configuration, a plurality of media access controldedicated parameters. The media access control dedicated parameters maycomprise a plurality of time alignment timer values. Each of theplurality of time alignment timer values may be associated with a uniquecell group in the wireless device. A time alignment timer of a cellgroup in the plurality of cell groups may start or restart in responseto the wireless device receiving a timing advance command to adjustuplink transmission timing of the cell group.

According to some of the various embodiments, uplink transmissions bythe wireless device in the primary cell group may employ a firstsynchronization signal transmitted on the primary cell. Uplinktransmissions in the secondary cell group may employ a secondsynchronization signal on the reference secondary cell as a secondarytiming reference.

According to some of the various embodiments, prior to transmitting thecontrol message(s), a first signaling bearer may be established betweenthe base station and the first wireless device. The establishing maycomprise the base station transmitting a control message to the firstwireless device on the primary cell. Prior to transmitting the controlmessage(s), the base station may receive a plurality of radio capabilityparameters from the first wireless device on the first signaling beareron the primary cell. The plurality of radio capability parameters mayindicate that the wireless device supports configuration of theplurality of cell groups.

According to some of the various embodiments, a base station maytransmit control message(s) to a first wireless device at block 1500.The plurality of base stations may be compatible with LTE release 11 orabove.

According to some of the various embodiments, a plurality of timingadvance commands may be transmitted to a plurality of wireless devicesat block 1502 for adjusting uplink transmission timing by the pluralityof wireless devices. Each of the plurality of wireless devices mayoperate in a mode. The mode may be one of: a first mode employable byall of the plurality of wireless devices; and a second mode employableonly by a subset of the plurality of wireless devices.

According to some of the various embodiments, the timing advancecommand(s) may be interpreted by a wireless device in the plurality ofwireless devices being addressed by timing advance command(s). Theinterpretation may depend on the mode in which the wireless device isoperating. Each of the plurality of timing advance commands may consistof: a subheader, a control element, and a two-bit information element.The subheader may comprise the same logical channel identifier value forthe each of the plurality of timing advance commands. The controlelement may comprise a timing advance value. The two-bit informationelement may be interpreted as: a cell group index associated to a cellgroup adjusting uplink transmission timing if the wireless device isoperating in the second mode; and/or reserved bits if the wirelessdevice is operating in the first mode.

According to some of the various embodiments, in an exampleimplementation, the first mode may be unconfigurable with a plurality ofcell groups and the second mode may be configurable with a plurality ofcell groups. In another example, the first mode may be configured to becompatible with at least release: 8, 9 or 10 of LTE technology; orrelease 11 of LTE technology without multiple time alignment capability.The second mode may be configured to be compatible with release 11 ofLTE technology with multiple time alignment capability. In anotherexample, the first mode may be configured to be compatible with at leastrelease 8, 9 or 10 of LTE technology. The second mode may be configuredto be compatible with release 11 of LTE technology.

According to some of the various embodiments, prior to transmitting theat least one control message, a first signaling bearer may beestablished between the base station and the first wireless device. Theestablishing may comprise the base station transmitting a controlmessage to the first wireless device on the primary cell. Prior totransmitting the at least one control message, the base station mayreceive a plurality of radio capability parameters from the firstwireless device on the first signaling bearer on the primary cell. Theplurality of radio capability parameters may indicate that the wirelessdevice supports configuration of the second mode. The base station mayreceive a plurality of radio capability parameters from the secondwireless device on the first signaling bearer on the primary cell. Theplurality of radio capability parameters may indicate that the wirelessdevice supports configuration of the first mode.

According to some of the various embodiments, the base station maytransmit control message(s) to a first wireless device operating in thesecond mode. The control message(s) may be configured to cause in thefirst wireless device configuration of a plurality of cells. Theplurality of cells may comprise a primary cell and at least onesecondary cell.

According to some of the various embodiments, the control message(s) maybe configured to cause in the first wireless device, a cell group indexfor a secondary cell in the plurality of cells. The cell group index mayidentify one of a plurality of cell groups. The plurality of cell groupsmay comprise a primary cell group and a secondary cell group. Theprimary cell group may comprise a first subset of the plurality ofcells. The first subset may comprise the primary cell. The secondarycell group may comprise a second subset of the at least one secondarycell.

According to some of the various embodiments, a base station in awireless network may transmit a plurality of timing advance commands toa plurality of wireless devices for adjusting uplink transmission timingby the plurality of wireless devices. Each of the plurality of wirelessdevices may operate in a mode. The mode may be a first mode or a secondmode. The first mode may be employable by all of the plurality ofwireless devices. The second mode may be employable only by a subset ofthe plurality of wireless devices.

According to some of the various embodiments, the timing advancecommand(s) may be interpreted by a wireless device in the plurality ofwireless devices being addressed by timing advance command(s). Theinterpretation may depend on the mode in which the wireless device isoperating. Each of the plurality of timing advance commands may consistof: a subheader, a control element, and a two-bit information element.The subheader may comprise the same logical channel identifier value forthe each of the plurality of timing advance commands. The controlelement may comprise a timing advance value. The two-bit informationelement may be interpreted differently depending on the wireless deviceoperating mode.

According to some of the various embodiments, a first signaling bearermay be established between the base station and the first wirelessdevice prior to transmitting the at least one control message. Theestablishing may comprise the base station transmitting a controlmessage to the first wireless device on the primary cell. The basestation may receive a plurality of radio capability parameters from thefirst wireless device on the first signaling bearer on the primary cellprior to transmitting the at least one control message. The plurality ofradio capability parameters may indicate that the wireless devicesupports configuration of the second mode.

According to some of the various embodiments, the base station maytransmit control message(s) to a first wireless device operating in thesecond mode. The control message(s) may be configured to cause in thefirst wireless device configuration of a plurality of cells. Theplurality of cells may comprise a primary cell and at least onesecondary cell.

According to some of the various embodiments, the control message(s) maybe configured to cause in the first wireless device a cell group indexfor each cell in the plurality of cells. The cell group index mayidentify one of a plurality of cell groups. The plurality of cell groupsmay comprise a primary cell group and a secondary cell group. Theprimary cell group may comprise a first subset of the plurality ofcells. The first subset may comprise the primary cell. The secondarycell group may comprise a second subset of the at least one secondarycell.

According to some of the various aspects of embodiments, the randomaccess procedure may be initiated by a PDCCH order or by the MACsublayer itself. Random access procedure on an SCell may be initiated bya PDCCH order. If a UE receives a PDCCH transmission consistent with aPDCCH order masked with its C-RNTI (radio network temporary identifier),and for a specific serving cell, the UE may initiate a random accessprocedure on this serving cell. For random access on the PCell a PDCCHorder or RRC optionally indicate the ra-PreambleIndex and thera-PRACH-MaskIndex; and for random access on an SCell, the PDCCH orderindicates the ra-PreambleIndex with a value different from zero and thera-PRACH-MaskIndex. For the pTAG preamble transmission on PRACH andreception of a PDCCH order may only be supported for PCell.

According to some of the various aspects of embodiments, the proceduremay use some of the following information: a) the available set of PRACHresources for the transmission of the random access preamble,prach-ConfigIndex., b) for PCell, the groups of random access preamblesand/or the set of available random access preambles in each group, c)for PCell, the preambles that are contained in random access preamblesgroup A and Random Access Preambles group B are calculated, d) the RAresponse window size ra-ResponseWindowSize, e) the power-ramping factorpowerRampingStep, f) the maximum number of preamble transmissionpreambleTransMax, g) the initial preamble powerpreambleInitialReceivedTargetPower, h) the preamble format based offsetDELTA_PREAMBLE, i) for PCell, the maximum number of Msg3 HARQtransmissions maxHARQ-Msg3Tx, j) for PCell, the Contention ResolutionTimer mac-ContentionResolutionTimer. These parameters may be updatedfrom upper layers before each Random Access procedure is initiated.

According to some of the various aspects of embodiments, the RandomAccess procedure may be performed as follows: Flush the Msg3 buffer; setthe PREAMBLE_TRANSMISSION_COUNTER to 1; set the backoff parameter valuein the UE to 0 ms; for the RN (relay node), suspend any RN subframeconfiguration; proceed to the selection of the Random Access Resource.There may be one Random Access procedure ongoing at any point in time.If the UE receives a request for a new Random Access procedure whileanother is already ongoing, it may be up to UE implementation whether tocontinue with the ongoing procedure or start with the new procedure.

According to some of the various aspects of embodiments, the RandomAccess Resource selection procedure may be performed as follows. Ifra-PreambleIndex (Random Access Preamble) and ra-PRACH-MaskIndex (PRACHMask Index) have been explicitly signalled and ra-PreambleIndex is notzero, then the Random Access Preamble and the PRACH Mask Index may bethose explicitly signalled. Otherwise, the Random Access Preamble may beselected by the UE.

The UE may determine the next available subframe containing PRACHpermitted by the restrictions given by the prach-ConfigIndex, the PRACHMask Index and physical layer timing requirements (a UE may take intoaccount the possible occurrence of measurement gaps when determining thenext available PRACH subframe). If the transmission mode is TDD and thePRACH Mask Index is equal to zero, then if ra-PreambleIndex wasexplicitly signalled and it was not 0 (i.e., not selected by MAC), thenrandomly select, with equal probability, one PRACH from the PRACHsavailable in the determined subframe. Else, the UE may randomly select,with equal probability, one PRACH from the PRACHs available in thedetermined subframe and the next two consecutive subframes. If thetransmission mode is not TDD or the PRACH Mask Index is not equal tozero, a UE may determine a PRACH within the determined subframe inaccordance with the requirements of the PRACH Mask Index. Then the UEmay proceed to the transmission of the Random Access Preamble.

PRACH mask index values may range for example from 0 to 16. PRACH maskindex value may determine the allowed PRACH resource index that may beused for transmission. For example, PRACH mask index 0 may mean that allPRACH resource indices are allowed; or PRACH mask index 1 may mean thatPRACH resource index 0 may be used. PRACH mask index may have differentmeaning in TDD and FDD systems.

The random-access procedure may be performed by UE settingPREAMBLE_RECEIVED_TARGET_POWER topreambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep.The UE may instruct the physical layer to transmit a preamble using theselected PRACH, corresponding RA-RNTI, preamble index andPREAMBLE_RECEIVED_TARGET_POWER.

According to some of the various aspects of embodiments, once the randomaccess preamble is transmitted and regardless of the possible occurrenceof a measurement gap, the UE may monitor the PDCCH of the PCell forrandom access response(s) identified by the RA-RNTI (random access radionetwork identifier) a specific RA-RNTI defined below, in the randomaccess response (RAR) window which may start at the subframe thatcontains the end of the preamble transmission plus three subframes andhas length ra-ResponseWindowSize subframes. The specific RA-RNTIassociated with the PRACH in which the Random Access Preamble istransmitted, is computed as: RA-RNTI=1+t_id+10*f_id. Where t_id is theindex of the first subframe of the specified PRACH (0≤t_id<10), and f_idis the index of the specified PRACH within that subframe, in ascendingorder of frequency domain (0≤f_id<6). The UE may stop monitoring forRAR(s) after successful reception of a RAR containing random accesspreamble identifiers that matches the transmitted random accesspreamble.

According to some of the various aspects of embodiments, if a downlinkassignment for this TTI (transmission time interval) has been receivedon the PDCCH for the RA-RNTI and the received TB (transport block) issuccessfully decoded, the UE may regardless of the possible occurrenceof a measurement gap: if the RAR contains a backoff indicator (BI)subheader, set the backoff parameter value in the UE employing the BIfield of the backoff indicator subheader, else, set the backoffparameter value in the UE to zero msec. If the RAR contains a randomaccess preamble identifier corresponding to the transmitted randomaccess preamble, the UE may consider this RAR reception successful andapply the following actions for the serving cell where the random accesspreamble was transmitted: process the received riming advance commandfor the cell group in which the preamble was transmitted, indicate thepreambleInitialReceivedTargetPower and the amount of power rampingapplied to the latest preamble transmission to lower layers (i.e.,(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep); process thereceived uplink grant value and indicate it to the lower layers; theuplink grant is applicable to uplink of the cell in which the preamblewas transmitted. If ra-PreambleIndex was explicitly signalled and it wasnot zero (e.g., not selected by MAC), consider the random accessprocedure successfully completed. Otherwise, if the Random AccessPreamble was selected by UE MAC, set the Temporary C-RNTI to the valuereceived in the RAR message. When an uplink transmission is required,e.g., for contention resolution, the eNB may not provide a grant smallerthan 56 bits in the Random Access Response.

According to some of the various aspects of embodiments, if no RAR isreceived within the RAR window, or if none of all received RAR containsa random access preamble identifier corresponding to the transmittedrandom access preamble, the random access response reception mayconsidered not successful. If RAR is not received, UE may incrementPREAMBLE_TRANSMISSION_COUNTER by 1. IfPREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and random accesspreamble is transmitted on the PCell, then UE may indicate a randomaccess problem to upper layers (RRC). This may result in radio linkfailure. If PREAMBLE_TRANSMISSION_COUNTER=preambleTransMax+1 and therandom access preamble is transmitted on an SCell, then UE may considerthe random access procedure unsuccessfully completed. UE may stay in RRCconnected mode and keep the RRC connection active even though a randomaccess procedure unsuccessfully completed on a secondary TAG. Accordingto some of the various aspects of embodiments, at completion of therandom access procedure, the UE may discard explicitly signalledra-PreambleIndex and ra-PRACH-MaskIndex, if any; and flush the HARQbuffer used for transmission of the MAC PDU in the Msg3 buffer. Inaddition, the RN may resume the suspended RN subframe configuration, ifany.

According to some of the various aspects of embodiments, the UE may havea configurable timer timeAlignmentTimer per TAG. The timeAlignmentTimeris used to control how long the UE considers the Serving Cells belongingto the associated TAG to be uplink time aligned (in-sync). When a TimingAdvance Command MAC control element is received, the UE may apply theriming advance command for the indicated TAG, and start or restart thetimeAlignmentTimer associated with the indicated TAG. When a timingadvance command is received in a RAR message for a serving cellbelonging to a TAG and if the random access preamble was not selected byUE MAC, the UE may apply the timing advance command for this TAG, andmay start or restart the timeAlignmentTimer associated with this TAG.When a timeAlignmentTimer associated with the pTAG expires, the UE may:flush all HARQ buffers for all serving cells; notify RRC to releasePUCCH/SRS for all serving cells; clear any configured downlinkassignments and uplink grants; and consider all runningtimeAlignmentTimers as expired. When a timeAlignmentTimer associatedwith an sTAG expires, then for all Serving Cells belonging to this TAG,the UE may flush all HARQ buffers; and notify RRC to release SRS. The UEmay not perform any uplink transmission on a serving Cell except therandom access preamble transmission when the timeAlignmentTimerassociated with the TAG to which this serving cell belongs is notrunning. When the timeAlignmentTimer associated with the pTAG is notrunning, the UE may not perform any uplink transmission on any servingcell except the random access preamble transmission on the PCell. A UEstores or maintains N_TA (current timing advance value of an sTAG) uponexpiry of associated timeAlignmentTimer. The UE may apply a receivedtiming advance command MAC control element and starts associatedtimeAlignmentTimer. Transmission of the uplink radio frame number i fromthe UE may start (N_(TA)+N_(TA offset))×T_(s) seconds before the startof the corresponding downlink radio frame at the UE, where0≤N_(TA)≤20512. In an example implementation, N_(TA offset)=0 for framestructure type 1 (FDD) and N_(TA offset)=624 for frame structure type 2(TDD).

According to some of the various aspects of embodiments, upon receptionof a timing advance command for a TAG containing the primary cell, theUE may adjust uplink transmission timing for PUCCH/PUSCH/SRS of theprimary cell based on the received timing advance command. The ULtransmission timing for PUSCH/SRS of a secondary cell may be the same asthe primary cell if the secondary cell and the primary cell belong tothe same TAG. Upon reception of a timing advance command for a TAG notcontaining the primary cell, the UE may adjust uplink transmissiontiming for PUSCH/SRS of secondary cells in the TAG based on the receivedtiming advance command where the UL transmission timing for PUSCH/SRS isthe same for all the secondary cells in the TAG.

The timing advance command for a TAG may indicate the change of theuplink timing relative to the current uplink timing for the TAG asmultiples of 16T_(s) (T_(s): sampling time unit). The start timing ofthe random access preamble may obtained employing a downlinksynchronization time in the same TAG. In case of random access response,an 11-bit timing advance command, TA, for a TAG may indicate NTA valuesby index values of TA=0, 1, 2, . . . , 1282, where an amount of the timealignment for the TAG may be given by N_(TA)=TA×16. In other cases, a6-bit timing advance command, TA, for a TAG may indicate adjustment ofthe current N_(TA) value, N_(TA,old), to the new NTA value, N_(TA,new),by index values of TA=0, 1, 2, . . . , 63, whereN_(TA,new)=N_(TA,old)+(TA−31)×16. Here, adjustment of NTA value by apositive or a negative amount indicates advancing or delaying the uplinktransmission timing for the TAG by a given amount respectively. For atiming advance command received on subframe n, the correspondingadjustment of the uplink transmission timing may apply from thebeginning of subframe n+6. For serving cells in the same TAG, when theUE's uplink PUCCH/PUSCH/SRS transmissions in subframe n and subframe n+1are overlapped due to the timing adjustment, the UE may completetransmission of subframe n and not transmit the overlapped part ofsubframe n+1. If the received downlink timing changes and is notcompensated or is only partly compensated by the uplink timingadjustment without timing advance command, the UE may change N_(TA)accordingly.

Downlink frames and subframes of downlink carriers are time aligned (bythe base station) in carrier aggregation and multiple TAG configuration.Time alignment errors may be tolerated to some extent. For example, forintra-band contiguous carrier aggregation, time alignment error may notexceed 130 ns. In another example, for intra-band non-contiguous carrieraggregation, time alignment error may not exceed 260 ns. In anotherexample, for inter-band carrier aggregation, time alignment error maynot exceed 1.3 μs.

The UE may have capability to follow the frame timing change of theconnected base station. The uplink frame transmission may take place(N_(TA)+N_(TA offset))×T_(s) before the reception of the first detectedpath (in time) of the corresponding downlink frame from the referencecell. The UE may be configured with a pTAG containing the PCell. ThepTAG may also contain one or more SCells, if configured. The UE may alsobe configured with one or more sTAGs, in which case the pTAG may containone PCell and the sTAG may contain at least one SCell with configureduplink. In pTAG, UE may use the PCell as the reference cell for derivingthe UE transmit timing for cells in the pTAG. The UE may employ asynchronization signal on the reference cell to drive downlink timing.When a UE is configured with an sTAG, the UE may use an activated SCellfrom the sTAG for deriving the UE transmit timing for cell in the sTAG.

In at least one of the various embodiments, uplink physical channel(s)may correspond to a set of resource elements carrying informationoriginating from higher layers. The following example uplink physicalchannel(s) may be defined for uplink: a) Physical Uplink Shared Channel(PUSCH), b) Physical Uplink Control Channel (PUCCH), c) Physical RandomAccess Channel (PRACH), and/or the like. Uplink physical signal(s) maybe used by the physical layer and may not carry information originatingfrom higher layers. For example, reference signal(s) may be consideredas uplink physical signal(s). Transmitted signal(s) in slot(s) may bedescribed by one or several resource grids including, for example,subcarriers and SC-FDMA or OFDMA symbols. Antenna port(s) may be definedsuch that the channel over which symbol(s) on antenna port(s) may beconveyed and/or inferred from the channel over which other symbol(s) onthe same antenna port(s) is/are conveyed. There may be one resource gridper antenna port. The antenna port(s) used for transmission of physicalchannel(s) or signal(s) may depend on the number of antenna port(s)configured for the physical channel(s) or signal(s).

According to some of the various aspects of embodiments, cell search maybe the procedure by which a wireless device may acquire time andfrequency synchronization with a cell and may detect the physical layerCell ID of that cell (transmitter). An example embodiment forsynchronization signal and cell search is presented below. A cell searchmay support a scalable overall transmission bandwidth corresponding to 6resource blocks and upwards. Primary and secondary synchronizationsignals may be transmitted in the downlink and may facilitate cellsearch. For example, 504 unique physical-layer cell identities may bedefined using synchronization signals. The physical-layer cellidentities may be grouped into 168 unique physical-layer cell-identitygroups, group(s) containing three unique identities. The grouping may besuch that physical-layer cell identit(ies) is part of a physical-layercell-identity group. A physical-layer cell identity may be defined by anumber in the range of 0 to 167, representing the physical-layercell-identity group, and a number in the range of 0 to 2, representingthe physical-layer identity within the physical-layer cell-identitygroup. The synchronization signal may include a primary synchronizationsignal and a secondary synchronization signal.

According to some of the various embodiments, physical downlink controlchannel(s) may carry transport format, scheduling assignments, uplinkpower control, and other control information. PDCCH may support multipleformats. Multiple PDCCH packets may be transmitted in a subframe.According to some of the various embodiments, scheduling controlpacket(s) may be transmitted for packet(s) or group(s) of packetstransmitted in downlink shared channel(s). Scheduling control packet(s)may include information about subcarriers used for packettransmission(s). PDCCH may also provide power control commands foruplink channels. PDCCH channel(s) may carry a plurality of downlinkcontrol packets in subframe(s). Enhance PDCCH may be implemented in acell as an option to carrier control information. According to some ofthe various embodiments, PHICH may carry the hybrid-ARQ (automaticrepeat request) ACK/NACK.

Other arrangements for PCFICH, PHICH, PDCCH, enhanced PDCCH, and/orPDSCH may be supported. The configurations presented here are forexample purposes. In another example, resources PCFICH, PHICH, and/orPDCCH radio resources may be transmitted in radio resources including asubset of subcarriers and pre-defined time duration in each or some ofthe subframes. In an example, PUSCH resource(s) may start from the firstsymbol. In another example embodiment, radio resource configuration(s)for PUSCH, PUCCH, and/or PRACH (physical random access channel) may usea different configuration. For example, channels may be timemultiplexed, or time/frequency multiplexed when mapped to uplink radioresources.

According to some of the various aspects of embodiments, the physicallayer random access preamble may comprise a cyclic prefix of length Tcpand a sequence part of length Tseq. The parameter values may bepre-defined and depend on the frame structure and a random accessconfiguration. In an example embodiment, Tcp may be 0.1 msec, and Tseqmay be 0.9 msec. Higher layers may control the preamble format. Thetransmission of a random access preamble, if triggered by the MAC layer,may be restricted to certain time and frequency resources. The start ofa random access preamble may be aligned with the start of thecorresponding uplink subframe at a wireless device.

According to an example embodiment, random access preambles may begenerated from Zadoff-Chu sequences with a zero correlation zone,generated from one or several root Zadoff-Chu sequences. In anotherexample embodiment, the preambles may also be generated using otherrandom sequences such as Gold sequences. The network may configure theset of preamble sequences a wireless device may be allowed to use.According to some of the various aspects of embodiments, there may be amultitude of preambles (e.g. 64) available in cell(s). From the physicallayer perspective, the physical layer random access procedure mayinclude the transmission of random access preamble(s) and random accessresponse(s). Remaining message(s) may be scheduled for transmission by ahigher layer on the shared data channel and may not be considered partof the physical layer random access procedure. For example, a randomaccess channel may occupy 6 resource blocks in a subframe or set ofconsecutive subframes reserved for random access preamble transmissions.

According to some of the various embodiments, the following actions maybe followed for a physical random access procedure: 1) layer 1 proceduremay be triggered upon request of a preamble transmission by higherlayers; 2) a preamble index, a target preamble received power, acorresponding RA-RNTI (random access-radio network temporary identifier)and/or a PRACH resource may be indicated by higher layers as part of arequest; 3) a preamble transmission power P_PRACH may be determined; 4)a preamble sequence may be selected from the preamble sequence set usingthe preamble index; 5) a single preamble may be transmitted usingselected preamble sequence(s) with transmission power P_PRACH on theindicated PRACH resource; 6) detection of a PDCCH with the indicated RARmay be attempted during a window controlled by higher layers; and/or thelike. If detected, the corresponding downlink shared channel transportblock may be passed to higher layers. The higher layers may parsetransport block(s) and/or indicate an uplink grant to the physicallayer(s).

According to some of the various aspects of embodiments, a random accessprocedure may be initiated by a physical downlink control channel(PDCCH) order and/or by the MAC sublayer in a wireless device. If awireless device receives a PDCCH transmission consistent with a PDCCHorder masked with its radio identifier, the wireless device may initiatea random access procedure. Preamble transmission(s) on physical randomaccess channel(s) (PRACH) may be supported on a first uplink carrier andreception of a PDCCH order may be supported on a first downlink carrier.

Before a wireless device initiates transmission of a random accesspreamble, it may access one or many of the following types ofinformation: a) available set(s) of PRACH resources for the transmissionof a random access preamble; b) group(s) of random access preambles andset(s) of available random access preambles in group(s); c) randomaccess response window size(s); d) power-ramping factor(s); e) maximumnumber(s) of preamble transmission(s); f) initial preamble power; g)preamble format based offset(s); h) contention resolution timer(s);and/or the like. These parameters may be updated from upper layers ormay be received from the base station before random access procedure(s)may be initiated.

According to some of the various aspects of embodiments, a wirelessdevice may select a random access preamble using available information.The preamble may be signaled by a base station or the preamble may berandomly selected by the wireless device. The wireless device maydetermine the next available subframe containing PRACH permitted byrestrictions given by the base station and the physical layer timingrequirements for TDD or FDD. Subframe timing and the timing oftransmitting the random access preamble may be determined based, atleast in part, on synchronization signals received from the base stationand/or the information received from the base station. The wirelessdevice may proceed to the transmission of the random access preamblewhen it has determined the timing. The random access preamble may betransmitted on a second plurality of subcarriers on the first uplinkcarrier.

According to some of the various aspects of embodiments, once a randomaccess preamble is transmitted, a wireless device may monitor the PDCCHof a primary carrier for random access response(s), in a random accessresponse window. There may be a pre-known identifier in PDCCH thatidentifies a random access response. The wireless device may stopmonitoring for random access response(s) after successful reception of arandom access response containing random access preamble identifiersthat matches the transmitted random access preamble and/or a randomaccess response address to a wireless device identifier. A base stationrandom access response may include a time alignment command. Thewireless device may process the received time alignment command and mayadjust its uplink transmission timing according the time alignment valuein the command. For example, in a random access response, a timealignment command may be coded using 11 bits, where an amount of thetime alignment may be based on the value in the command. In an exampleembodiment, when an uplink transmission is required, the base stationmay provide the wireless device a grant for uplink transmission.

If no random access response is received within the random accessresponse window, and/or if none of the received random access responsescontains a random access preamble identifier corresponding to thetransmitted random access preamble, the random access response receptionmay be considered unsuccessful and the wireless device may, based on thebackoff parameter in the wireless device, select a random backoff timeand delay the subsequent random access transmission by the backoff time,and may retransmit another random access preamble.

According to some of the various aspects of embodiments, a wirelessdevice may transmit packets on an uplink carrier. Uplink packettransmission timing may be calculated in the wireless device using thetiming of synchronization signal(s) received in a downlink. Uponreception of a timing alignment command by the wireless device, thewireless device may adjust its uplink transmission timing. The timingalignment command may indicate the change of the uplink timing relativeto the current uplink timing. The uplink transmission timing for anuplink carrier may be determined using time alignment commands and/ordownlink reference signals.

According to some of the various aspects of embodiments, a timealignment command may indicate timing adjustment for transmission ofsignals on uplink carriers. For example, a time alignment command mayuse 6 bits. Adjustment of the uplink timing by a positive or a negativeamount indicates advancing or delaying the uplink transmission timing bya given amount respectively.

For a timing alignment command received on subframe n, the correspondingadjustment of the timing may be applied with some delay, for example, itmay be applied from the beginning of subframe n+6. When the wirelessdevice's uplink transmissions in subframe n and subframe n+1 areoverlapped due to the timing adjustment, the wireless device maytransmit complete subframe n and may not transmit the overlapped part ofsubframe n+1.

According to some of the various aspects of embodiments, controlmessage(s) or control packet(s) may be scheduled for transmission in aphysical downlink shared channel (PDSCH) and/or physical uplink sharedchannel PUSCH. PDSCH and PUSCH may carry control and datamessage(s)/packet(s). Control message(s) and/or packet(s) may beprocessed before transmission. For example, the control message(s)and/or packet(s) may be fragmented or multiplexed before transmission. Acontrol message in an upper layer may be processed as a data packet inthe MAC or physical layer. For example, system information block(s),radio resource control messages, and data traffic may be scheduled fortransmission in PDSCH.

According to some of the various aspects of embodiments, a wirelessdevice may be preconfigured with one or more carriers. When the wirelessdevice is configured with more than one carrier, the base station and/orwireless device may activate and/or deactivate the configured carriers.One of the carriers (the primary carrier) may always be activated. Othercarriers may be deactivated by default and/or may be activated by a basestation when needed. A base station may activate and deactivate carriersby sending an activation/deactivation MAC control element. Furthermore,the UE may maintain a carrier deactivation timer per configured carrierand deactivate the associated carrier upon its expiry. The same initialtimer value may apply to instance(s) of the carrier deactivation timer.The initial value of the timer may be configured by a network. Theconfigured carriers (unless the primary carrier) may be initiallydeactivated upon addition and after a handover.

According to some of the various aspects of embodiments, if a wirelessdevice receives an activation/deactivation MAC control elementactivating the carrier, the wireless device may activate the carrier,and/or may apply normal carrier operation including: sounding referencesignal transmissions on the carrier (if the carrier is uplink timealigned), CQI (channel quality indicator)/PMI(precoding matrixindicator)/RI(ranking indicator) reporting for the carrier, PDCCHmonitoring on the carrier, PDCCH monitoring for the carrier, start orrestart the carrier deactivation timer associated with the carrier,and/or the like. If the device receives an activation/deactivation MACcontrol element deactivating the carrier, and/or if the carrierdeactivation timer associated with the activated carrier expires, thebase station or device may deactivate the carrier, and may stop thecarrier deactivation timer associated with the carrier, and/or may flushHARQ buffers associated with the carrier.

If PDCCH on a carrier scheduling the activated carrier indicates anuplink grant or a downlink assignment for the activated carrier, thedevice may restart the carrier deactivation timer associated with thecarrier. When a carrier is deactivated, the wireless device may nottransmit SRS (sounding reference signal) for the carrier, may not reportCQI/PMI/RI for the carrier, may not transmit on UL-SCH for the carrier,may not monitor the PDCCH on the carrier, and/or may not monitor thePDCCH for the carrier.

A process to assign subcarriers to data packets may be executed by a MAClayer scheduler. The decision on assigning subcarriers to a packet maybe made based on data packet size, resources required for transmissionof data packets (number of radio resource blocks), modulation and codingassigned to data packet(s), QoS required by the data packets (i.e. QoSparameters assigned to data packet bearer), the service class of asubscriber receiving the data packet, or subscriber device capability, acombination of the above, and/or the like.

According to some of the various aspects of embodiments, packets may bereferred to service data units and/or protocols data units at Layer 1,Layer 2 and/or Layer 3 of the communications network. Layer 2 in an LTEnetwork may include three sub-layers: PDCP sub-layer, RLC sub-layer, andMAC sub-layer. A layer 2 packet may be a PDCP packet, an RLC packet or aMAC layer packet. Layer 3 in an LTE network may be Internet Protocol(IP) layer, and a layer 3 packet may be an IP data packet. Packets maybe transmitted and received via an air interface physical layer. Apacket at the physical layer may be called a transport block. Many ofthe various embodiments may be implemented at one or many differentcommunication network layers. For example, some of the actions may beexecuted by the PDCP layer and some others by the MAC layer or PHYlayer.

According to some of the various aspects of embodiments, a radio bearermay be a GBR (guaranteed bit rate) bearer and/or a non-GBR bearer. A GBRand/or guaranteed bit rate bearer may be employed for transfer ofreal-time packets, and/or a non-GBR bearer may be used for transfer ofnon-real-time packets. The non-GBR bearer may be assigned a plurality ofattributes including: a scheduling priority, an allocation and retentionpriority, a portable device aggregate maximum bit rate, and/or the like.These parameters may be used by the scheduler in scheduling non-GBRpackets. GBR bearers may be assigned attributes such as delay, jitter,packet loss parameters, and/or the like.

According to some of the various aspects of embodiments, the transmitterin the disclosed embodiments of the present invention may be a wirelessdevice (also called user equipment), a base station (also calledeNodeB), a relay node transmitter, and/or the like. The receiver in thedisclosed embodiments of the present invention may be a wireless device(also called user equipment-UE), a base station (also called eNodeB), arelay node receiver, and/or the like.

According to some of the various aspects of embodiments, the MAC layerin some wireless device(s) may report buffer size(s) of either a singleLogical Channel Group (LCG) or a group of LCGs to a base station. An LCGmay be a group of logical channels identified by an LCG ID. The mappingof logical channel(s) to LCG may be set up during radio configuration.Buffer status report(s) may be used by a MAC scheduler to assign radioresources for packet transmission from wireless device(s). HARQ and ARQprocesses may be used for packet retransmission to enhance thereliability of radio transmission and reduce the overall probability ofpacket loss.

In this specification, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” In this specification,the term “may” is to be interpreted as “may, for example,” In otherwords, the term “may” is indicative that the phrase following the term“may” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}.

In this specification, parameters (Information elements: IEs) maycomprise one or more objects, and each of those objects may comprise oneor more other objects. For example, if parameter (IE) N comprisesparameter (IE) M, and parameter (IE) M comprises parameter (IE) K, andparameter (IE) K comprises parameter (information element) J, then, forexample, N comprises K, and N comprises J.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e. hardware with a biological element) or acombination thereof, all of which are behaviorally equivalent. Forexample, modules may be implemented as a software routine written in acomputer language configured to be executed by a hardware machine (suchas C, C++, Fortran, Java, Basic, Matlab or the like) or amodeling/simulation program such as Simulink, Stateflow, GNU Octave, orLab VIEWMathScript. Additionally, it may be possible to implementmodules using physical hardware that incorporates discrete orprogrammable analog, digital and/or quantum hardware. Examples ofprogrammable hardware comprise: computers, microcontrollers,microprocessors, application-specific integrated circuits (ASICs); fieldprogrammable gate arrays (FPGAs); and complex programmable logic devices(CPLDs). Computers, microcontrollers and microprocessors are programmedusing languages such as assembly, C, C++ or the like. FPGAs, ASICs andCPLDs are often programmed using hardware description languages (HDL)such as VHSIC hardware description language (VHDL) or Verilog thatconfigure connections between internal hardware modules with lesserfunctionality on a programmable device. Finally, it needs to beemphasized that the above mentioned technologies are often used incombination to achieve the result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the spirit and scope. In fact, after reading theabove description, it will be apparent to one skilled in the relevantart(s) how to implement alternative embodiments. Thus, the presentembodiments should not be limited by any of the above describedexemplary embodiments. In particular, it should be noted that, forexample purposes, the above explanation has focused on the example(s)using FDD communication systems. However, one skilled in the art willrecognize that embodiments of the invention may also be implemented inTDD communication systems. The disclosed methods and systems may beimplemented in wireless or wireline systems. The features of variousembodiments presented in this invention may be combined. One or manyfeatures (method or system) of one embodiment may be implemented inother embodiments. Only a limited number of example combinations areshown to indicate to one skilled in the art the possibility of featuresthat may be combined in various embodiments to create enhancedtransmission and reception systems and methods.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112, paragraph 6. Claims that do not expressly include the phrase“means for” or “step for” are not to be interpreted under 35 U.S.C. 112,paragraph 6.

1. A wireless device comprising: one or more processors; and memorystoring instructions that, when executed by the one or more processors,cause the wireless device to: receive configuration informationassociated with sounding reference signal (SRS) transmission via asecondary cell of a secondary cell group; receive an activation commandto activate the secondary cell; after receiving the activation command,transmit a random access preamble via the secondary cell group; receivea random access response comprising: a timing advance command (TAC) forthe secondary cell group; and a power control command; and afterapplying the TAC, transmit a plurality of SRSs via the secondary cellbased on the configuration information, wherein transmission powerassociated with transmission of a first SRS, of the plurality of theSRSs, is based on the power control command.
 2. The wireless device ofclaim 1, wherein the instructions, when executed by the one or moreprocessors, further cause the wireless device to receive, beforetransmitting the random access preamble, a second control command. 3.The wireless device of claim 1, wherein the instructions, when executedby the one or more processors, further cause the wireless device to dropat least one SRS, of the plurality of SRSs, based on one or moreconditions.
 4. The wireless device of claim 1, wherein the wirelessdevice is configured to not transmit any of the plurality of the SRSsvia the secondary cell during a time period between receiving theactivation command and receiving the TAC.
 5. The wireless device ofclaim 1, wherein the instructions, when executed by the one or moreprocessors, further cause the wireless device to drop transmission of anSRS, of the plurality of SRSs, in a subframe of the secondary cellduring a time period that the wireless device is power-limited.
 6. Thewireless device of claim 1, wherein the instructions, when executed bythe one or more processors, further cause the wireless device to applythe TAC, wherein application of the TAC facilitates alignment of basestation reception timing of uplink signals of the secondary cell group.7. The wireless device of claim 1, wherein the instructions, whenexecuted by the one or more processors, further cause the wirelessdevice to configure a time alignment timer for each of a plurality ofcell groups to start, or restart, based on the wireless device:receiving a first TAC to adjust uplink transmission timing of acommanded cell group of the plurality of cell groups.
 8. The wirelessdevice of claim 1, wherein a plurality of cell groups comprises a firstcell group and the secondary cell group, and wherein: uplinktransmission timing associated with the first cell group is based on acell of the first cell group; and uplink transmission timing associatedwith the secondary cell group is based on a cell of the secondary cellgroup.
 9. The wireless device of claim 1, wherein the instructions, whenexecuted by the one or more processors, further cause the wirelessdevice to: transmit a first SRS, of the plurality of SRSs, in a firstsubframe of the secondary cell, if the wireless device has sufficientpower to transmit one or more first data packets in parallel with thefirst SRS; and drop a configured transmission of a second SRS, of theplurality of SRSs, in a second subframe of the secondary cell, if thewireless device does not have sufficient power to transmit one or moresecond data packets in parallel with the second SRS.
 10. The wirelessdevice of claim 1, wherein the instructions, when executed by the one ormore processors, further cause the wireless device to receive at leastone message comprising: a cell parameter associated with the secondarycell and comprising an indication of a cell group index; and at leastone configuration parameter of at least one of the plurality of SRSs.11. A method comprising: receiving, by a wireless device, configurationinformation associated with sounding reference signal (SRS) transmissionvia a secondary cell of a secondary cell group; receiving an activationcommand to activate the secondary cell; after the receiving theactivation command, transmitting a random access preamble via thesecondary cell group; receiving a random access response comprising: atiming advance command (TAC) for the secondary cell group; and a powercontrol command; and after applying the TAC, transmitting a plurality ofSRSs via the secondary cell based on the configuration information,wherein transmission power associated with transmission of a first SRS,of the plurality of the SRSs, is based on the power control command. 12.The method of claim 11, further comprising receiving, before thetransmitting the random access preamble, a second control command. 13.The method of claim 11, further comprising dropping at least one SRS, ofthe plurality of SRSs, based on one or more conditions.
 14. The methodof claim 11, wherein the wireless device is configured to not transmitany of the plurality of the SRSs via the secondary cell during a timeperiod between the receiving the activation command and receiving theTAC.
 15. The method of claim 11, further comprising droppingtransmission of an SRS, of the plurality of SRSs, in a subframe of thesecondary cell during a time period that the wireless device ispower-limited.
 16. The method of claim 11, further comprising applyingthe TAC, wherein applying the TAC facilitates alignment of receptiontiming of uplink signals of the secondary cell group.
 17. The method ofclaim 11, further comprising configuring, by the wireless device, a timealignment timer for each of a plurality of cell groups to start, orrestart, based on the wireless device: receiving a first TAC to adjustuplink transmission timing of a commanded cell group of the plurality ofcell groups.
 18. The method of claim 11, wherein a plurality of cellgroups comprises a first cell group and the secondary cell group, andwherein: uplink transmission timing associated with the first cell groupis based on a cell of the first cell group; and uplink transmissiontiming associated with the secondary cell group is based on a cell ofthe secondary cell group.
 19. The method of claim 11, furthercomprising: transmitting a first SRS, of the plurality of SRSs, in afirst subframe of the secondary cell, if the wireless device hassufficient power to transmit one or more first data packets in parallelwith the first SRS; and dropping a configured transmission of a secondSRS, of the plurality of SRSs, in a second subframe of the secondarycell, if the wireless device does not have sufficient power to transmitone or more second data packets in parallel with the second SRS.
 20. Themethod of claim 11, further comprising receiving at least one messagecomprising: a cell parameter associated with the secondary cell andcomprising an indication of a cell group index; and at least oneconfiguration parameter of at least one of the plurality of SRSs.
 21. Asystem comprising: a wireless device; and a base station; wherein thebase station is configured to: transmit configuration informationassociated with sounding reference signal (SRS) transmission via asecondary cell of a secondary cell group; and transmit an activationcommand to activate the secondary cell; and wherein the wireless deviceis configured to: after receiving the activation command, transmit arandom access preamble via the secondary cell group; receive a randomaccess response comprising: a timing advance command (TAC) for thesecondary cell group; and a power control command; and after applyingthe TAC, transmit a plurality of SRSs via the secondary cell based onthe configuration information, wherein transmission power associatedwith transmission of a first SRS, of the plurality of the SRSs, is basedon the power control command.
 22. The system of claim 21, wherein thewireless device is further configured to receive, before transmittingthe random access preamble, a second control command.
 23. The system ofclaim 21, wherein the wireless device is further configured to drop atleast one SRS, of the plurality of SRSs, based on one or moreconditions.
 24. The system of claim 21, wherein the wireless device isconfigured to not transmit any of the plurality of the SRSs via thesecondary cell during a time period between receiving the activationcommand and receiving the TAC.
 25. The system of claim 21, wherein thewireless device is further configured to drop transmission of an SRS, ofthe plurality of SRSs, in a subframe of the secondary cell during a timeperiod that the wireless device is power-limited.
 26. The system ofclaim 21, wherein the wireless device is further configured to apply theTAC, wherein application of the TAC facilitates alignment of basestation reception timing of uplink signals of the secondary cell group.27. The system of claim 21, wherein the wireless device is furtherconfigured to configure a time alignment timer for each of a pluralityof cell groups to start, or restart, based on the wireless device:receiving a first TAC to adjust uplink transmission timing of acommanded cell group of the plurality of cell groups.
 28. The system ofclaim 21, wherein a plurality of cell groups comprises a first cellgroup and the secondary cell group, and wherein: uplink transmissiontiming associated with the first cell group is based on a cell of thefirst cell group; and uplink transmission timing associated with thesecondary cell group is based on a cell of the secondary cell group. 29.The system of claim 21, wherein the wireless device to: transmit a firstSRS, of the plurality of SRSs, in a first subframe of the secondarycell, if the wireless device has sufficient power to transmit one ormore first data packets in parallel with the first SRS; and drop aconfigured transmission of a second SRS, of the plurality of SRSs, in asecond subframe of the secondary cell, if the wireless device does nothave sufficient power to transmit one or more second data packets inparallel with the second SRS.
 30. The system of claim 21, wherein thebase station is further configured to transmit at least one messagecomprising: a cell parameter associated with the secondary cell andcomprising an indication of a cell group index; and at least oneconfiguration parameter of at least one of the plurality of SRSs.
 31. Anon-transitory computer-readable medium storing instructions that, whenexecuted, configure a wireless device to: receive configurationinformation associated with sounding reference signal (SRS) transmissionvia a secondary cell of a secondary cell group; receive an activationcommand to activate the secondary cell; after receiving the activationcommand, transmit a random access preamble via the secondary cell group;receive a random access response comprising: a timing advance command(TAC) for the secondary cell group; and a power control command; andafter applying the TAC, transmit a plurality of SRSs via the secondarycell based on the configuration information, wherein transmission powerassociated with transmission of a first SRS, of the plurality of theSRSs, is based on the power control command.
 32. The non-transitorycomputer-readable medium of claim 31, wherein the instructions, whenexecuted, further configure the wireless device to receive, beforetransmitting the random access preamble, a second control command. 33.The non-transitory computer-readable medium of claim 31, wherein theinstructions, when executed, further configure the wireless device todrop at least one SRS, of the plurality of SRSs, based on one or moreconditions.
 34. The non-transitory computer-readable medium of claim 31,wherein the instructions, when executed, configure the wireless deviceto not transmit any of the plurality of the SRSs via the secondary cellduring a time period between receiving the activation command andreceiving the TAC.
 35. The non-transitory computer-readable medium ofclaim 31, wherein the instructions, when executed, further configure thewireless device to drop transmission of an SRS, of the plurality ofSRSs, in a subframe of the secondary cell during a time period that thewireless device is power-limited.
 36. The non-transitorycomputer-readable medium of claim 31, wherein the instructions, whenexecuted, further configure the wireless device to apply the TAC,wherein application of the TAC facilitates alignment of base stationreception timing of uplink signals of the secondary cell group.
 37. Thenon-transitory computer-readable medium of claim 31, wherein theinstructions, when executed, further configure the wireless device toconfigure a time alignment timer for each of a plurality of cell groupsto start, or restart, based on the wireless device: receiving a firstTAC to adjust uplink transmission timing of a commanded cell group ofthe plurality of cell groups.
 38. The non-transitory computer-readablemedium of claim 31, wherein a plurality of cell groups comprises a firstcell group and the secondary cell group, and wherein: uplinktransmission timing associated with the first cell group is based on acell of the first cell group; and uplink transmission timing associatedwith the secondary cell group is based on a cell of the secondary cellgroup.
 39. The non-transitory computer-readable medium of claim 31,wherein the instructions, when executed, further configure the wirelessdevice to: transmit a first SRS, of the plurality of SRSs, in a firstsubframe of the secondary cell, if the wireless device has sufficientpower to transmit one or more first data packets in parallel with thefirst SRS; and drop a configured transmission of a second SRS, of theplurality of SRSs, in a second subframe of the secondary cell, if thewireless device does not have sufficient power to transmit one or moresecond data packets in parallel with the second SRS.
 40. Thenon-transitory computer-readable medium of claim 31, wherein theinstructions, when executed, further configure the wireless device toreceive at least one message comprising: a cell parameter comprisesassociated with the secondary cell and comprising an indication of acell group index; and at least one configuration parameter of at leastone of the plurality of SRS s.